Edit: Sorry, will post Hijack this Log asap.
My computer has been running unusually slow lately, and things such as clicking links and loading pages cause Firefox to freeze up and take 30 seconds to load (things it usually took 1 or 2 seconds to do). Even while typing a post, the browser will randomly freeze.
Anyways, the problem isn't just with web-surfing, and most of my windows take a long time to switch between them.
So I've done some antivrus scans, yet all the scans I've done said everything is clean (Avira, McAfee, and Windows Defender. Trying AVG now.). Although I still think the problem might be caused by a trojan since I got a warning a few days when I attempted a download; of course I canceled the download, but it must have been too late already as firefox froze up right after I did and I had to manually shut down my computer.
In any case, what do you all recommend I do next? I'd appreciate any help I can get. Thanks for reading.
Windows Vista Home Premium (Serv. Pack 1) (64-bit)