I had this same problem in the past, something like 3-4 years ago IIRC.
I think I formatted and reinstalled XP to solve the problem, probably I had some bad filter entry in the registry which made some conflicts with others. I preferred to format than to inspect the PC to find the cause of the problem. Problem solved.
Now I have just formatted again my PC, and with latest BSplayer release and latest K-Lite Mega Codec Pack (yes, I had fallen to the dark side) I still have this issue. BSplayer sends a crash report telling me that there where an access violation to the module ntdll.dll
At the end the filter is added, but I can't verify it until next opening of the preferences page.
I don't know who the culprit is... I hope to find it...
Anyway if I add the filters to the Black/White list the crash doesn't occur
