Have to reformat due to virus infection

I have a paid subscription on my desktop and run the free version on my laptop that I use infrequently. The desktop is riddled with Generic trojanhorses of all numbers, Open Candy.AVG catches these every time I sign on but something got past and corrupted my AMD Catalyst Install Manager. It does not allow use of any icons on the desktop including the Start button. Not sure how all these got on computer. I am very careful about clicking on links anyone sends me and the only thing I upgraded was the Microsoft Office Picture Manager. After that everything went downhill. Could this have gotten in that way? Any solutions before I reformat? Makes me mad to think that this happened on the computer with the PAID subscription.