Help with a possible virus

Hello,

I bought a laptop under a year ago. It is an acer, and there is a huge problem with it at the moment. First off I don't have a Recovery CD because circit city, where I got it, put their own system stuff on it and the recovery cd they gave me was a 2 disk and it failed. So I had to reformat my computer about 6 months ago. Anyway, that isn't the problem I just wanted to inform so someone wouldn't say of just use the recovery cd.

The PROBLEM is when I am in normal mode, I cannot access my spyboy search and destory or my avg. I also cannot get onto the Internet. I do however play an online game which comes with it's own kit and can get onto that and MIRC. I tried to start firefox and it comes up but then it goes away, when I click on it again it says that Firefox is already running, please close blah blah blah. I try to find if it is and it is not. Then I try to get on IE and it freezes my whole computer.

So I think it is a virus but then again it could be something else. I have a tower which is clean. So what is the problem and can I fix it?

Thanks
Michelle