Running Panda was a good thing. At least no known rootkits on your PC.

It's very hard to diagnose PC problems blind and a port monitoring program [what is going in or out over the internet] would not be much use to you as it's all a bit complex.

I would still suggest you post your problem on http://www.spywarewarrior.com/index.php as this group is the best of the best if any nasties are involved.