Long story made short!
Just received a second hand PC, was working fine until I loaded some new programs and setup broadband.
Thereafter when it starts it goes into Windows error checking mode, saying that a file is missing, and continues to reboot itself without entering windows. Then after entering windows, it reboots itself after about an 20 minutes of use.
It was suggested that I replace the harddrive which I did.
I am now trying to load windows NT 200 again on it. However, halfway through setup it reboots ityself. It always does this half-way through setting up the network connections.
I did read once that te solution could be to replace a cable, I'm not sure which one.
If you have heard of this or have another suggestion, please let me know.