BleepingComputer.com: Sudden in-game lag, yet computer is fine

I have recently been experiencing in-game lag in the program/games I use; ventrilo, warcraft3, and counterstrike source. After everything I've tried, those games still lag and my computer seems fine. The last thing I can think of what might be causing the problem is that I manually deleted 2 big MMORPG files instead of uninstalling them the same day, then later that day is when I started lagging.
The lag only occurs in-game, and while I'm in vent I can see that I have a high ping

-Highly doubt that I have a virus or anything of that sort, I've had AVG for a long time and I have it run a scan everyday at 3 a.m.
-I've ran Ccleaner and cleaned up a lot of the junk on my comp.
-I've also ran a disk defrag.