Double-check everything, specially IDE cables/connections. DOSBox cannot do that and thus, cannot be held responsible for any damage. Some nasty sheer coincidence.

DOSBox does not modify any of your computer's settings or even integrate itself into Windows.

It sounds more likely to be a hardware failure, virus infection, or freak accident.

Is your BIOS able to detect your hard drive?

Sounds like a bad HD.....

The hard drive is detected and it even runs as a slave on my second pc.
The moment I chose to boot from that hard disk on either computer it restarts in a continuous cycle, obviously the windows file system has been hosed !

How far does it get before it restarts?

Sorry, the last post was mine.. I wasn't logged in.

It just detects the drives at the very start and doesn't move to the next screen, where normally the option to boot from a floppy would appear, it restarts right when the screen usually changes.

There are ways to repair the MBR, but I don't know what they are off the top of my head. Some Google searching will probably turn up some info though.

It also may be a good idea to see what the partition table looks like using Partition Magic, Norton Ghost, fdisk, or some other tool.

Just boot from your Windows CD and go into the console to repair the MBR.

Go into the console and then what? I'm sure it won't do it automatically...

Type in HELP

and then it's FIXMBR or FIXBOOT IIRC. Been a long time since I played around with recovery console.