Don't know what the heck is going on. Whenever I try to play a game, the system intermittently slows down, and my game along with it. It doesn't matter whether the game is recent or 10 years old. I attempted to play StarCraft earlier, whose only requirements are a Pentium 90 MHz processor and 16 MB of RAM, and the problem still occured.
I'm running Windows XP with a Pentium 4 1.7 GHz processor and 512 MB of RAM. I have a NVidia GeForce 2 graphics card, which should be more than enough for what I need. I've got a 70 GB hard drive, with 40 GB free space.
I ran Lavasoft Ad-Aware and Spy Bot Search & Destroy to get rid of all spyware/adware, cleaned out the registry, ran Norton Anti-Virus, which found nothing, and shut down all unnecessary system processes. Nothing seems to help.
I'm clean out of ideas here, and I've been racking my brain for days. Any suggestions?