I installed PCLinuxOS, KDE version, on a Packard Bell MH35 laptop after trying several other distros (Debian, another distro, others I can't recall). PCLOS was the only one that automatically recognized the nasty old video chipset (SiS 771/671) and used the proper resolution without forcing me to do headache-inducing things like manually editing xorg.conf.

It mostly works, in that I can browse the internet, write, do most things I'd want to do with it... except watch videos. VLC and Mplayer both start and play the video, but if I drag their window around or hit the fullscreen key X crashes and I find myself looking at the login screen. This doesn't happen if I drag/resize Firefox playing a Youtube video; it seems exclusive to standalone media players. I've no clue how to tackle this. What do I do?

Check under preferences which video output is selected. You will normally get a list of available video output modules. Try them one by one and see if anything works properly. Is there a possibility that the video card runs out of memory when trying to play fullscreen?