problem counter-strike.

Well, my problem is that almost 3 or 4 months I'm playing the game in software mode counter-strike.
The reason is that once in the computer entered a virus and had to send the computer on which technical fix but also formatting, operating system change as the computer came back home I entered the counter-strike and is set to when I download, ie, mode 16-bit software, etc. But when I wanted to change software to OpenGL and 16bit to 32bit would not let me, I saltava up a sign that said (The Specified video mode is not supported. the game will now run in software mode)
from already thank you very much.