User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.2) Gecko/20100316 Firefox/3.6.2

Computer use:
The computer in question is mainly a backup server and is managed mostly remotely using SSH. Anything done using SSH works fine, as do all operations done locally using terminal.
Problem description:
After what seems like a variable, but low number of manipulations (1-10) using the mouse, the screen goes blank and my session is closed. The problem seems associated with a window-create call and can be just a cursor hover, say over the F (lower left). After the session crash, I can SSH into the box from another Fedora machine and do whatever I like, but locally the mouse and keyboard seem unresponsive. After an occurance the X11 process is gone from the list of processes (top).

Reproducible: Always

Steps to Reproduce:
1.login to a GUI session
2.open and close several windows. For example try to use Dolphin to "drill" down to a file.
3.
Actual Results:  
Eventually the screen goes blank, the keyboard and mouse are unresponsive. I am no longer logged on as determined by SSH from another Fedora box.

Expected Results:  
Successful use of a file.

General:
FC12 was installed onto a clean disk. 
Updated weekly, and continues to be so. 
Using KDE, but also has Gnome installed. 
At first this problem occured only rarely (2-3 times/week) with light local GUI use. Beginning about 5 or 6 updates ago, the problem has grown worse. At present it's only a matter of time before it occurs- within 10 minutes of logon to a fresh boot.

Diagnostic information:
The ABRT system does not catch this problem.
I have looked at the X11 logs and found the attached log after the occurance of the problem, but before any reboot or any other manipulation other than a cp. Note the last entries.
No other logs make any reference to the problem.
The problem occurs with both KDE and Gnome and after a reinstall of all of the X11 files and the Intel driver using yum.
I have tried using the last two kernel versions with no change.
I have tried "nomodeset" as a kernel parameter with no change in behavior.

Machine description:
Gateway series 310 machine
Integrated video using a 82845GV graphics and memory controller, described as "Intel Extreme Graphics controller".
2 Gigs of memory matched from Gateway's list of acceptable memory.
Celeron processor at 2.6 GHz.
2 500 Gig Western digital drives.
Running FC12 up to date.