I was on my in-law's PC that trying to merge a partion with Partition Magic (Merging with main C drive). During the merge process, I got an error. It told me to hit any key to exit and reboot. After doing so & trying to load back into Windows, I got an error that it couldn't find a file and that I should insert the setup disk and run the repair utility. I did so, but it just takes me to the C:/Windows prompt. What do I do next to try and repiar my installation of Windows XP?