How old is your computer?
I've had similar problems before with at least 3 computers and here's what I did:
If your disk usage is going up to 100% in your performance tab in task manager, try wiping the HDD by writing zeroes then reinstall the operating system.
You can download a bootable .ISO of mini tool partition magic to perform the wipe HDD by writing zeroes.
The purpose here is to remap your HDD and in theory it would work as if it was new. Why wipe in zeroes? Well, simply formatting the HDD will not remap the sectors of your HDD which eventually causes it to perform slow, especially if your HDD is at least 3 years old. Believe it or not, old data stays in HDD unless they're overwritten by something else, hence we write zeroes...