Is my system unstable?

[MaxFusion16]

I just built an athlon xp 1800 system with shuttle ak31a board and crucial 256mb ddr ram. I frequently get error messages in windows xp saying some error has occured, and the application has to close. I can't figure why, it's just occuring too frequently. On a normal day, I would be surfing the web, and all of a sudden, an error would occur. So I restart IE, then it might work for a while, then it would just crashed again. I have already reinstalled a fresh copy of windows xp pro, it's still the same. I suspect that my system is unstable, but I'm not overclocking anything, and the cpu temp is only 40c. Please tell me what's wrong.
Thanks

 

[Gix]

i used to get that error too. try reformatting

 

[QTPie]

Did you install VIA 4-in-1 service pack? It could help , and install all updates, too

 

[MaxFusion16]

yes I did install the via 4 in 1 drive, and I have done a complete format and fresh install of windows xp, but I still get error messages. Usually the errors occur after a period of operation. I suspect that my cpu is overheating, but the motherboard temp reading is only around 40c. Also my heatsink doesn't feel very hot, it's just warm. So I don't understand, would this happen if the cpu is overheating? The athlon xp 1800 cpu is rated up to 90c, this shouldn't happen.