I was having the same problems with my system. It started after installing the "recommended" upgrades to WinXP from MS's website. I am not sure which one of the files is responsible. I haven't done any upgrades/patches/anything to XP since my last re-format, reinstall. I also haven't had the problems of my video stuttering either. Hope this was of some use.
<b>Never underestimate the power of stupid people in large numbers.</b>