Just done chkdsk c: /r and Windows replaced a lot of bad clusters in a lot of files mainly .dll files and a few .msi & .ini files.
Would you say the HDD is shot and to get a replacement PC under warranty anyway?
It just let me install the .NET Framework 1.1 which it definately wouldnt do before.
It also let me install the ATI Catalyst control centre as a result of installing the above.
However it wont let me install & update the latest drivers for my GFX card and it wont let me install MYST IV as it keeps rebooting or says the file is corrupt. The HDD does sound awfuly noisy to me, so I think I am going to leave it for a complete exchange.
Big thanks to everyone for their help. I will let you know the outcome when I get my exchange sorted.
Thanks a lot guys!!!!