Description of problem:
I can't seem to find a specific time or website where it happens, but this does
keep happening:

*** glibc detected *** /usr/lib64/firefox-3.0/firefox: double free or corruption
(fasttop): 0x0000000000bf6c40 ***
======= Backtrace: =========
/lib64/libc.so.6[0x3ff74793c8]
/lib64/libc.so.6(cfree+0x76)[0x3ff747ba06]
/usr/lib64/libhunspell-1.2.so.0(_ZN8HunspellD1Ev+0xbd)[0x300c4225ed]
/usr/lib64/xulrunner-1.9/libxul.so[0x300fbee849]
/usr/lib64/xulrunner-1.9/libxul.so[0x300fbed6f0]
/usr/lib64/xulrunner-1.9/libxul.so[0x300fc2112c]
/usr/lib64/xulrunner-1.9/libxul.so[0x300fbf38d6]
/usr/lib64/xulrunner-1.9/libxul.so[0x300fc21571]
/usr/lib64/xulrunner-1.9/libxul.so(NS_ShutdownXPCOM_P+0x193)[0x300fbfc577]
/usr/lib64/xulrunner-1.9/libxul.so[0x300f4210f7]
/usr/lib64/xulrunner-1.9/libxul.so(XRE_main+0x1e3a)[0x300f423a42]
/usr/lib64/firefox-3.0/firefox(__gxx_personality_v0+0x565)[0x401665]
/lib64/libc.so.6(__libc_start_main+0xe6)[0x3ff741e3f6]
/usr/lib64/firefox-3.0/firefox(__gxx_personality_v0+0x59)[0x401159]
======= Memory map: ========
00110000-0011c000 r-xp 00000000 08:02 40987                             
/lib64/libnss_files-2.8.90.so
0011c000-0031b000 ---p 0000c000 08:02 40987                             
/lib64/libnss_files-2.8.90.so
0031b000-0031c000 r--p 0000b000 08:02 40987                             
/lib64/libnss_files-2.8.90.so
0031c000-0031d000 rw-p 0000c000 08:02 40987                             
/lib64/libnss_files-2.8.90.so
00400000-00409000 r-xp 00000000 08:02 679943                            
/usr/lib64/firefox-3.0/firefox
00608000-0060a000 rw-p 00008000 08:02 679943                            
/usr/lib64/firefox-3.0/firefox
0060a000-0066a000 r-xp 00000000 08:02 22976                             
/usr/lib64/gtk-2.0/modules/libgail.so
0066a000-00869000 ---p 00060000 08:02 22976                             
/usr/lib64/gtk-2.0/modules/libgail.so
00869000-0086b000 rw-p 0005f000 08:02 22976                             
/usr/lib64/gtk-2.0/modules/libgail.so
0086b000-0086c000 rw-p 0086b000 00:00 0 
00946000-039b7000 rw-p 00946000 00:00 0                                  [heap]
41851000-41852000 ---p 41851000 00:00 0 
41852000-42252000 rw-p 41852000 00:00 0 
42252000-42253000 ---p 42252000 00:00 0 
42253000-42c53000 rw-p 42253000 00:00 0 
44a56000-44a57000 ---p 44a56000 00:00 0 
44a57000-45457000 rw-p 44a57000 00:00 0 
3000000000-30000bf000 r-xp 00000000 08:02 146731                        
/usr/lib64/libgdk-x11-2.0.so.0.1304.0
30000bf000-30002bf000 ---p 000bf000 08:02 146731                        
/usr/lib64/libgdk-x11-2.0.so.0.1304.0
30002bf000-30002c4000 rw-p 000bf000 08:02 146731                        
/usr/lib64/libgdk-x11-2.0.so.0.1304.0
3000400000-300043c000 r-xp 00000000 08:02 41218                         
/lib64/libdbus-1.so.3.4.0
300043c000-300063b000 ---p 0003c000 08:02 41218                         
/lib64/libdbus-1.so.3.4.0
300063b000-300063c000 r--p 0003b000 08:02 41218                         
/lib64/libdbus-1.so.3.4.0
300063c000-300063d000 rw-p 0003c000 08:02 41218                         
/lib64/libdbus-1.so.3.4.0
3000800000-3000816000 r-xp 00000000 08:02 41612                         
/lib64/libgcc_s-4.3.1-20080708.so.1
3000816000-3000a15000 ---p 00016000 08:02 41612                         
/lib64/libgcc_s-4.3.1-20080708.so.1
3000a15000-3000a16000 rw-p 00015000 08:02 41612                         
/lib64/libgcc_s-4.3.1-20080708.so.1
3000c00000-3000c12000 r-xp 00000000 08:02 45816                         
/lib64/libresolv-2.8.90.so
3000c12000-3000e12000 ---p 00012000 08:02 45816                         
/lib64/libresolv-2.8.90.so
3000e12000-3000e13000 r--p 00012000 08:02 45816                         
/lib64/libresolv-2.8.90.so
3000e13000-3000e14000 rw-p 00013000 08:02 45816                         
/lib64/libresolv-2.8.90.so
3000e14000-3000e16000 rw-p 3000e14000 00:00 0 
3001000000-3001003000 r-xp 00000000 08:02 45825                         
/lib64/libuuid.so.1.2
3001003000-3001203000 ---p 00003000 08:02 45825                         
/lib64/libuuid.so.1.2
3001203000-3001204000 rw-p 00003000 08:02 45825                         
/lib64/libuuid.so.1.2
3001400000-300141f000 r-xp 00000000 08:02 1769874                       
/usr/lib64/libdbus-glib-1.so.2.1.0
300141f000-300161e000 ---p 0001f000 08:02 1769874                       
/usr/lib64/libdbus-glib-1.so.2.1.0
300161e000-3001620000 rw-p 0001e000 08:02 1769874                       
/usr/lib64/libdbus-glib-1.so.2.1.0
3001800000-3001817000 r-xp 00000000 08:02 1770409                       
/usr/lib64/libICE.so.6.3.0
3001817000-3001a16000 ---p 00017000 08:02 1770409                       
/usr/lib64/libICE.so.6.3.0
3001a16000-3001a18000 rw-p 00016000 08:02 1770409                       
/usr/lib64/libICE.so.6.3.0
3001a18000-3001a1b000 rw-p 3001a18000 00:00 0 
3001c00000-3001c08000 r-xp 00000000 08:02 1770410                       
/usr/lib64/libSM.so.6.0.0
3001c08000-3001e07000 ---p 00008000 08:02 1770410                       
/usr/lib64/libSM.so.6.0.0
3001e07000-3001e08000 rw-p 00007000 08:02 1770410                       
/usr/lib64/libSM.so.6.0.0
3002000000-3002002000 r-xp 00000000 08:02 45817                         
/lib64/libcom_err.so.2.1
3002002000-3002201000 ---p 00002000 08:02 45817                         
/lib64/libcom_err.so.2.1
3002201000-3002202000 rw-p 00001000 08:02 45817                         
/lib64/libcom_err.so.2.1
3002400000-3002550000 r-xp 00000000 08:02 141270                        
/usr/lib64/libxml2.so.2.6.32
3002550000-300274f000 ---p 00150000 08:02 141270                        
/usr/lib64/libxml2.so.2.6.32
300274f000-3002758000 rw-p 0014f000 08:02 141270                        
/usr/lib64/libxml2.so.2.6.32
3002758000-300275a000 rw-p 3002758000 00:00 0 
3002800000-3002802000 r-xp 00000000 08:02 45815                         
/lib64/libkeyutils-1.2.so
3002802000-3002a01000 ---p 00002000 08:02 45815                         
/lib64/libkeyutils-1.2.so
3002a01000-3002a02000 rw-p 00001000 08:02 45815                         
/lib64/libkeyutils-1.2.so
3002c00000-3002d40000 r-xp 00000000 08:02 45818                         
/lib64/libcrypto.so.0.9.8g
3002d40000-3002f3f000 ---p 00140000 08:02 45818                         
/lib64/libcrypto.so.0.9.8g
3002f3f000-3002f60000 rw-p 0013f000 08:02 45818                         
/lib64/libcrypto.so.0.9.8g
3002f60000-3002f63000 rw-p 3002f60000 00:00 0 
3003000000-3003024000 r-xp 00000000 08:02 140353                        
/usr/lib64/libk5crypto.so.3.1
3003024000-3003223000 ---p 00024000 08:02 140353                        
/usr/lib64/libk5crypto.so.3.1
3003223000-3003225000 rw-p 00023000 08:02 140353                        
/usr/lib64/libk5crypto.so.3.1
3003400000-300349f000 r-xp 00000000 08:02 142032                        
/usr/lib64/libkrb5.so.3.3
300349f000-300369f000 ---p 0009f000 08:02 142032                        
/usr/lib64/libkrb5.so.3.3
300369f000-30036a3000 rw-p 0009f000 08:02 142032                        
/usr/lib64/libkrb5.so.3.3
3003800000-3003809000 r-xp 00000000 08:02 140023                        
/usr/lib64/libkrb5support.so.0.1
3003809000-3003a09000 ---p 00009000 08:02 140023                        
/usr/lib64/libkrb5support.so.0.1
3003a09000-3003a0a000 rw-p 00009000 08:02 140023                        
/usr/lib64/libkrb5support.so.0.1
3003c00000-3003c2e000 r-xp 00000000 08:02 143632                        
/usr/lib64/libgssapi_krb5.so.2.2
3003c2e000-3003e2d000 ---p 0002e000 08:02 143632                        
/usr/lib64/libgssapi_krb5.so.2.2
3003e2d000-3003e2f000 rw-p 0002d000 08:02 143632                        
/usr/lib64/libgssapi_krb5.so.2.2
3004000000-30040ee000 r-xp 00000000 08:02 1769659                       
/usr/lib64/libstdc++.so.6.0.10
30040ee000-30042ee000 ---p 000ee000 08:02 1769659                       
/usr/lib64/libstdc++.so.6.0.10
30042ee000-30042f5000 r--p 000ee000 08:02 1769659                       
/usr/lib64/libstdc++.so.6.0.10
30042f5000-30042f7000 rw-p 000f5000 08:02 1769659                       
/usr/lib64/libstdc++.so.6.0.10
30042f7000-300430a000 rw-p 30042f7000 00:00 0 
3004400000-3004449000 r-xp 00000000 08:02 40999                         
/lib64/libssl.so.0.9.8g
3004449000-3004648000 ---p 00049000 08:02 40999                         
/lib64/libssl.so.0.9.8g
3004648000-300464f000 rw-p 00048000 08:02 40999                         
/lib64/libssl.so.0.9.8g
3004800000-3004802000 r-xp 00000000 08:02 45822                         
/lib64/libutil-2.8.90.so
3004802000-3004a01000 ---p 00002000 08:02 45822                         
/lib64/libutil-2.8.90.so
3004a01000-3004a02000 r--p 00001000 08:02 45822                         
/lib64/libutil-2.8.90.so
3004a02000-3004a03000 rw-p 00002000 08:02 45822                         
/lib64/libutil-2.8.90.so
3004c00000-3004c5d000 r-xp 00000000 08:02 1769905                       
/usr/lib64/libORBit-2.so.0.1.0
3004c5d000-3004e5c000 ---p 0005d000 08:02 1769905                       
/usr/lib64/libORBit-2.so.0.1.0
3004e5c000-3004e6e000 rw-p 0005c000 08:02 1769905                       
/usr/lib64/libORBit-2.so.0.1.0
3004e6e000-3004e6f000 rw-p 3004e6e000 00:00 0 
3005000000-3005039000 r-xp 00000000

Version-Release number of selected component (if applicable):
firefox-3.0-1.fc10.x86_64
xulrunner-1.9-1.fc10.x86_64

How reproducible:
Sometimes

Steps to Reproduce:
1. Browse the web (unsure what provokes the problem)
2. Firefox hangs
  
Actual results:
Firefox is nonresponsive, closing the window and attempting to reopen Firefox
results in the "Firefox is already open" message. "killall -9 firefox" solves
the problem.

Expected results:
No crash

Additional info:
I have the flash plugin installed, I'm not sure if this would provoke the
problem. It's happened on sites without flash though, so I doubt this is the
problem.