Missing dll. File

Hello, I had a file named msnrwhxo.dll that was apparently a corrupted file. I have AVG Anti-Virus and it asked me if I wanted to quarantine the file. I pushed yes and it warned that me that if I quarantined the file that the system might crash. I went ahead and quarantined the file and my computer proceeded to reset/crash. When the computer was loading up again a window popped up that said " This application has failed to start because msnrwhxo.dll was not found. Re-installing the application may fix this problem." This message basically pops up for just about every program that I try to start. If I click it off enough times then most applications will pop-up, excpet Firefox, and a few others. What do I do???!!!