What happens is that the start up screen recognises the hard drive, says 00 USB devices configured and goes to an error screen giving the option of booting to in safe mode or to start windows normally. At this point the keyboard locks up and I'm unable to access safe mode either by pressing the cursor keys to highlight the option or F8 at any stage in the start up procedure. It seems that the USB devices simply shut down as the mouse and keyboard both go dead, although I am able to boot into the BIOS settings on previous screens.
When the 30 seconds have counted down to select an option the whole thing tries to reboot again and ends up on the same page.
I've tried the hard drive in a different computer and it works fine. I've tried different keyboards, different USB slots and disconnected everything not essential to the start up process to rule out CD drives, etc. I'm guessing that this could be a motherboard problem but would appreciate any input if people have come across similar problems?