I'm currently running on a custom built PC. Running on XP. I've got; LGA 775 Pentium 4 processor, 2 gigs DDR2 ram, GeForge 8600GTS graphics card, Some nVidia mobo (if it's necessary I can get the actual model), about 300gigs harddrive space. My problem is, my PCU usage is sitting at about.. 70%-100%. Less than 48 hours ago, this wasn't a problem, I was running all my games at 60fps+, no lag issues at all. And now, it's gotten to the point where opening new tabs in Firefox is causing my PC to freeze up. I've tried a few things in hopes of fixing this; Anti-virus software, making sure everything is hooked in properly, closing processes that weren't necessary, etc. Yet it's all gone without result. Are there any known fixes for this?