Many many many thanks everyone, I have just sent back they creative geforce under warranty. Since then I have refitted my old Matrox PCI and Voodoo 2 card and all has been fine. Hopefully it is the creative card, shall find out when I get a new one back, if it goes again then it must be something on the MOB/AGP slot. Will let you know when I get the new card,
Thanks again everyone