Well I was able to solve the problem by simply reinstalling win xp. I didn't switch any hardware in my pc. This only proves that this particular problem occures because of lots of different reasons. It is tough to determine the definite cause for this. I never experienced any kind of difficulties with my RAM stick (I'm on single channel) and I always thought it's a software/driver issue in my case. It is interesting though, that the athlon/via combination seems to be affected. (For the record I have Athlon 1900+, VIA KT333 Chipset). It could very well be a RAM issue, as well as pretty much anything else
. Who knows?