Right well, i have tried installing 4 different OS's (formatted before each). I have tried installing Windows 2000 Professional Windows 2000 Server Windows 2000 Advanced server Windows XP Professional edition The CD's are all fine, as i have tested them on another machine. The HDD is also working properly. I have tried using the "fixmbr" utility from the XP CD and the Windows 2k Pro CD, with no luck. I have disabled the onboard virus protection, didn't help either. Basically, the problem is that after the setup finishes formatting, and then copying files it is supposed to restart. Well it restarts, and when it is supposed to continue the setup from the files copied to the HDD, it says "error loading operation system". The HDD has had Linux installed on it before, not sure if that matters. I have deleted the SWAP partitions and everything and done a complete format so that shouldnt effect it. The system has worked fine about a year ago with Windows XP Pro installed on it. It has 512MB of SDRAM and a 1.15Ghz AMD Athlon protsessor. The Motherboard is some old type of ViaTech or something like that. Any help would be appreciated, and if you need any additional information feel free to ask. Thank you in advance.