Recently my quake.x11 developed problems.

It had always slight sound problem, see the sound section.

However once after using qspy and network playing,
it erased several files from by disk
and changed attributes of other files.
I had to recover from the rescue disk, the system would not boot up.

Later after I recompiled kernel to include APM
it would run once, but when tried to restart it
it would dump core.
After reboot it would run once again and then next time dump core again.
To solve the problem I boot with the original kernel before using quake.

After I play network game once some files disappeared
and few minutes later they reappeared.
Also twice programs liks 'cat' or 'sh' dump core.
Later I looked at the core - they could not 
load shared libraries.

Does anyone have any hints what may be the problem?
Could it be the incorrect sound driver?