PhilFrisbie, thanks for your response.
No hardware or software has changed in this PC though I have listed some symptoms below that may assist identifying the problem.
There are times when it will start to automatically reboot after running for around 3-4 days, sometimes when it does it will BSOD saying something about "win32k.sys is missing"
There have also been some occasions when booting the PC, it will stop during BIOS POST at the point "Detecting IDE drives ..." and it will progress no further. After power recycling the PC it will then detect the IDE drive and then boot up. Do you think this could this be a faulty drive or is it more likely to be a faulty IDE controller?
Thanks for your assistance.