Virus or another king of dangerous program installed in my PC.

A program self installed in my PC Two days laters and block the execution of: internet explorer, my computer icon and windows explorer. I use an anti-virus that found a virus and it deleted contaminated file. After that I reboot my computer and the problem continued. I tried to install an anti-spyware to detected the problem, but after I install it, I tried to execute the program it doesn’t work. The virus or other thing blocked it.
I would like to know, how can I solve this problems?
Thank you in advance.
Antonio Luiz Bergamo do Bomfim