All my google-foo had a hard time finding a fix for this problem:

ut2003-bin: xcb_lock.c:62: _XGetXCBBuffer: Assertion `((int) ((xcb_req) -
(dpy->request)) >= 0)' failed.

So I gave up on playing Unreal Tournament 2003 for a few weeks.
After testing some software, I went back and done a fresh install of Slackware 12, installed just the things I would use, and went on using my new version of slack as usual.

I went back and tried to get UT2k3 to run again today and got the same error, then after looking around I found this:
http://bugzilla.icculus.org/show_bug.cgi?id=3182

The just of it. get rid of ut2003/System/libSDL-1.2.so.0 and
ln -s /usr/lib/libSDL-1.2.so.0 /path/to/ut2003/System/

Fixed it right up.

If anyone tries this, I'd like to know if your sound is choppy.
And if so, did you find a fix? what?.

you legend ... i knew it was library related, but didn't even think to link against the system one.

cheers

If you are using alsa drivers, you might try increasing buffer_size and decreasing period_size in alsa config for the sound device that UT2k3 uses.

I don't know about UT2k3, but that has helped immensely for skipping sound for me in wine running games. I had to set my buffer_size to 32768 and period_size to 2048.

You might try something similar, here is the webpage i looked at:

http://alsa.opensrc.org/index.php/Dm..._Stuttering.3F