It all started when i tried upgrading my Windows XP Professional. After the "dynamic update" step, a notification screen told me that i was missing a file called "af0ugmvs.sys". I (foolishly) opted to skip the file and continue with the setup. The computer restarted to a multiboot screen with the options "Windows XP" and "Windows XP (setup)" with the default at the latter. Now, the computer shows the multiboot screen every time.
I really hope that someone can help me with this problem. I also apologize if i'm not clear with my description of the problem.