hmm.. since heat is not a problem.. and u mentioned that ur computer has always been unstable. Is your computer OEM or DIY? Ways the pc can hang will harddisk fault, for example mulitple bad sectors which causes corrupt data. Another i can think of will be faulty ram.. Correct me if i am wrong. Data when flows to the ram slot, its being diverted randomly among the modules found on it.. If u look @ the ram, there are afew black square chip-like stuff on it... looks like below. ______________ | (1) (2) (3) (4) | -------------------- Say, the 2nd module is faulty. When data is being randomly diverted to that module, information cannot be processed and hence causing computer to hang.