Is this an X bug?

[Bob Self]

I'm running Ubuntu linux and am getting lockups. When it 'locks up' sometimes I can login via
ssh, sometimes everything is halted. When I can log in I always find that X is stuck at 100% cpu.

I have found this in /var/log/Xorg.0.log.old after rebooting via a ssh connection.

[mi] EQ overflowing. The server is probably stuck in an infinite loop.

Backtrace:
0: /usr/bin/X (xorg_backtrace+0x3b) [0x80e937b]
1: /usr/bin/X (mieqEnqueue+0x1ab) [0x80e8b6b]
2: /usr/bin/X (xf86PostButtonEventP+0xcf) [0x80c29cf]
3: /usr/bin/X (xf86PostButtonEvent+0x6c) [0x80c2a7c]
4: /usr/lib/xorg/modules/input/evdev_drv.so (0x7d4000+0x4c67) [0x7d8c67]
5: /usr/bin/X (0x8048000+0x6d5bf) [0x80b55bf]
6: /usr/bin/X (0x8048000+0x122744) [0x816a744]
7: (vdso) (__kernel_sigreturn+0x0) [0x149400]

Does anyone know what this means?

thanks,
Bob