Description of problem:
When I unplug my USB sound card in very specific circumstances, the machine will hard lock.  I was able to get a crash dump with nmi watchdog.

Version-Release number of selected component (if applicable):
kernel-2.6.35.10-74.fc14.x86_64

How reproducible:
very; around 8/10 times; I was doing some triage to try to narrow down the steps to reproduce, so that number may be slightly inaccurate.

Steps to Reproduce:
1. boot machine
2. login
3. plug in USB sound card
4. Select the USB soundcard as the Pulseaudio input and output with System->Preferences->Sound->[Input|Output]->choose USB soundcard
5. start alsamixer, select USB card, adjust volume, leave alsamixer running
6. start firefox and make a call with Google Voice; hang up the call
7. unplug the USB soundcard


Actual results:
System immediately hangs; if NMI watchdog is configured, system dumps

Expected results:
No hang

Additional info:
I was able to open the crashdump and confirm that the backtrace seems to implicate the sound code [exception RIP: snd_pcm_pre_stop+21], but I am no longer a kernel guy, so my analysis is pretty much limited to that.

I'll attach the full backtrace as an attachment, but I can provide the dump and corresponding vmlinux if needed.

I'm happy to try out test kernels to see if it fixes things.  I've tried several times to reproduce it with Totem producing audio instead of Google Voice, but so far it has not reproduced.