lolz..... sorry I am not teasing you but your situation is really hilarious. Sometimes the computers behave in a totally different and strange fashion. I have never come across such problem till date!!!
Get hold of the installation DVD
In the command prompt follow as given below
Type this without the quotes (")
"bootrec /fixmbr"
press enter.
Type this without the quotes (") again
"bootrec /FixBoot"
press Enter.
Now Restart and hope fully the prob would have been solved, if not I guess you have to reinstall. It has been a couple of days by now and I guess you would have already solved your problem