Coregen.exe problem (related to Silverlight)

WinXP Media Center Edition SP3... I was working on a friend's PC because he couldn't get any online videos that use Silverlight to play properly. I fixed that fairly easy and now the online videos play fine but when the PC is shut off or restarted, it hangs and barfs up a "coregen.exe cannot be closed" or "... has stopped responding" error. Uninstalling and re-installing Silverlight does not solve the problem, and this is NOT the first time that Silverlight has been the source of many headaches and problems on many other PCs.... any thoughts?

THX!