Thanks so far.
Am running Memtest as wel speak. Processor heatsing is fairly dusty bbut the fan is ok and the tems are no higher than normal.
Looks like I am going to have to bite the bullet and start re-seating stuff.
Its eitehr HDD or motherboard I guess (asuming the memory checks out). Anone know where I can get a compatable motherboard from, As Saab says cant get the exact same one now and I would like to keep the costs down otherwise I may as well go and buy a whole new PC.