Parity Check Fail - Exchange/Purchase Motherboard

After approx. 18 months of usage my Vaio VGN-FZ18m became somehow too hot which let to this error code: blue screen: "parity check failed, contact local vendor"; according to my vendor the MoBo got overheated and needs to be replaced: funny is, i could reinstall windows (vista) and it worked fine for like 10 minutes until it became too hot again; i tried to clean the fan and i will do that again with the build-down instruction i found on this board;

please, if anyone has some ideas on how to fix that problem or could tell me what to do with my vaio except for selling it on ebay i would be highly greatful!

thanks a lot in advance

ps: (i hope i could make myself clear, englisch is not my first language)