I'm running Fedora 15 64bit on a HP Elitebook 8740w. I have both Gnome and XFCE installed, and have only noticed this problem while using XFCE, but that may just be because I am using XFCE more than Gnome (that's another story - which I won't go into!).
Anyhow, twice in the past 3 days I've been in the middle of using the PC, and it has "locked up". By that I mean, using the keyboard and mouse have no effect. The display does not change, moving the mouse does not move the cursor from it's current position. And keyboard commands seem to have no effect (I've tried ctrl-alt-backspace, ctrl-alt-delete, and alt-F1, alt-F2, etc.). The only way I can continue using the computer is to hold in the power button until it powers off.
I suspect, but can't be sure, that it may only be a problem while I'm in XFCE. The reason I say this is that the first time it happened, I was trying to do a screen capture using The Gimp while in XFCE. Today I also tried to do another screen capture (again whilst in XFCE), and X kicked me out back to the login prompt. I then logged into Gnome and was able to successfully do the screen capture.
Later in the day I was using XFCE and programming in SpringSource Tool Suite, when the "lock up" occurred again, requiring me to switch the PC off again.
I've had a bit of a look in /var/log/Xorg.0.log.old and it finishes like this. I'm not sure if it is enough info to track down the problem though?
[ 1972.661] 0: /usr/bin/Xorg (xorg_backtrace+0x2f) [0x45e7ff]
[ 1972.661] 1: /usr/bin/Xorg (0x400000+0x62e86) [0x462e86]
[ 1972.661] 2: /lib64/libpthread.so.0 (0x34d1e00000+0xeeb0) [0x34d1e0eeb0]
[ 1972.661] 3: /lib64/libc.so.6 (0x34d1a00000+0x78b35) [0x34d1a78b35]
[ 1972.661] 4: /lib64/libc.so.6 (__libc_malloc+0x70) [0x34d1a7ab00]
[ 1972.661] 5: /usr/lib64/xorg/modules/libexa.so (0x7f580c59e000+0x8d27) [0x7f580c5a6d27]
[ 1972.661] 6: /usr/lib64/xorg/modules/libexa.so (0x7f580c59e000+0x13d30) [0x7f580c5b1d30]
[ 1972.661] 7: /usr/lib64/xorg/modules/libexa.so (0x7f580c59e000+0xffef) [0x7f580c5adfef]
[ 1972.661] 8: /usr/bin/Xorg (0x400000+0xd9c4d) [0x4d9c4d]
[ 1972.661] 9: /usr/bin/Xorg (0x400000+0xd46f5) [0x4d46f5]
[ 1972.661] 10: /usr/bin/Xorg (0x400000+0x2edb1) [0x42edb1]
[ 1972.661] 11: /usr/bin/Xorg (0x400000+0x22e1a) [0x422e1a]
[ 1972.661] 12: /lib64/libc.so.6 (__libc_start_main+0xed) [0x34d1a2139d]
[ 1972.662] 13: /usr/bin/Xorg (0x400000+0x23101) [0x423101]
[ 1972.662] Segmentation fault at address 0x40c8648
Fatal server error:
[ 1972.662] Caught signal 11 (Segmentation fault). Server aborting
Please consult the Fedora Project support
[ 1972.662] Please also check the log file at "/var/log/Xorg.0.log" for additional information.
So my question is basically - how do I debug this? Is there any particular files I should be looking at if it happens again?