My PC is infected

Hey, I am pretty sure that my pc is infected and at this time i cant install The Bitdefender app on my PC, 

Before that i had a couple of  Anti-virus programs installed Like  " Avira premium, AVG Internet security" but Both of them eventually went down and after running a full scan they couldnt catch anything.

at the beginning i thought it was a data corruption due to many times of power cut off, but when i was unable to install the anti-virus i was certain that this is an infection, apparently a good one.

The installation auto quits when i try to install it, Right now i am running a rescue CD, i'll update this post later today with the results.

If you guys could help me, Please because i have all my work on this PC

Thanks in advance.