Originally Posted by aimo3
How does MBR make for restarting?
If it can't boot to anything but it knows that something is there (i.e. - it's corrupt or missing files), the computer, instead of telling you there's no bootable device, will constantly restart in a booting loop.
Normally, unless you did something tricky when you install windows, it will create a 100MB "system reserved" partition in addition to installing Windows.
This is where the BCD (Boot Configuration Data) resides, so if it becomes corrupt, windows will not boot properly and possibly initiate an unending booting loop.
If you can access a command prompt with the bad drive, you can try repair it with the following commands:
bootrec /rebuildbcd *- I would say this one is optional