please help

Ok, i'll tell you my story:
Yesterday (7/21) i was booting up my laptop, and then suddenly it pop up unusually. I was ordered to load my OS (which is Vista), but i don't really know where. (it was like in folder system32 or something) So i click "Windows Startup Repair (WSR)". It repairs my computer and then shuts down. I booted up my PC again and it says "Windows failed to start...." and it gives me two suggestion: Run WSR, or Run windows normally. I decided to run windows normally because my OS is found during WSR. So, i thought the problem was finally resolved, but then... Some of my program was malfunctioning. Google Chrome, Acer Arcade Deluxe, Vegas Pro 9.0a, World of Goo, InkBall (which is inside the PC already), and probably many more. What happened? Can anyone help me how to resolve this problem? If you need info, just ask.

I don't think its a virus because during the last three days i didn't go to the internet.