|You didn't mention what anti-malware program(s) you have installed. Remember, you should only have 1 real-time running at a time. All others should be on-demand.|
Go to your computer manufacturer's website and download your device drivers, starting with the chipset, then the video card, then the rest.
@ grasshopper: If I recall correctly, a HDD will noticeably run slower once it reaches 90% capacity. Although not the cause in this case, it still has something to do with speed.
@ Ed: 3/4 of your links are incomplete.
Apologies if I don't respond to your reply immediately. I don't check this site daily, but you're welcome to PM me as a reminder.