Slow startup and slow execution

Hello all,

I am having a problem with my computer on startups and when I try to open programs. A few days ago, the computer was running like normal. Lately it takes forever to startup and to run programs. When I go to My Computer, it takes a while before it displays the contents. In the past few days I have preformed a disk cleanup, defrag and chkdsk scan. I have run full AVG Anti-Virus and Anti-Spyware, Ad-Aware and Spybot scans. I have gone to the Symantic website and preformed a full system scan for viruses. I downloaded CCleaner and cleaned everything out, including the registry. I even ran CWShredder. I am at a loss now as to why my computer is running so slow.

Did I miss anything?

Regards,

Scott:confused