|Btw you can get to your disk defrag by just going START>All Programs> Accessories>System Tools. |
You might very well just have too much **** running on your computer as a similar problem was happening to me when i had half a dozen services and startup programs running before i started trimming down a few.
I use a program called PC Decrapifier
Just go through it slowly and decide what you don't need. It's an excellent first step.
Then go START>RUN and type "MSCONFIG"
Go under the Startup tab and disable anything that is not essential at startup. You'll be surprised at how much faster things go. NOTE: Don't go crazy and disable things you don't recognize. That's a good way to get in trouble.
Go START>RUN and type "services.msc" It provides a detailed list of what programs do and give you the option of seeing what things do as well as gives you the option to just temporarily pause them to see if pandemonium follows. ;)
If nothing seems to work personally I would just get a backup drive, get anything important off and format the hard disk. I format mine once every 6 months and it keeps it running very well.