i completed the installation of windows seven, i was playing with it and then rebooted while rebooting, it shows this message in a dark background screen it says:

windows error recovery

Windows failed to start. A recent hardware or software change might be the cause.

If Windows files have been damaged or configured incorrectly, startup repair can help diagnose and fix the problem. if power was interrupted during startup, choose start windows normally.
(use the arrow kesy to hightlight your choice:)

Launch StartUp Repair (recommended)
Start Windows Normally

Description: Fix problem that are preveneting Windows from starting