When I first startup the PC nothing happens for a minute then the words 'Primary Drive 1 Not Found' appear. If I press F12 I get a list of boot devices. I choose Primary Hard Drive which then goes on to load the OS (Win XP Home) normally. I have checked the BIOS which is in order, Device Manager which shows everything as being fine and I have also opened up the PC to check that all the cables are secure. No new software or hardware has been added since this problem started. I don't why the PC doesn't just startup as normal.
A corrupt boot sector could also do this i.e. The MBR may need replacing from the back of the drive. When you create a Partition it Creates two MBR's one it boot's from and one at the end of the drive in case the first get's corrupt
Thanks again for all the info. I'm having second thoughts about replacing the MBR because on the Microsoft webpage that JonnyTub recommended it states "You must repair the MBR if it becomes corrupted and you can no longer access any volumes on that disk." The thing is I CAN access the disk (eventually). Creature of the nite, the data cable is secure so the pins must in line.