http://www.crucial.com/

Go to this site and click on "Scan My System". It will download the scan.

It will do that and show how much RAM you have, and suggest upgrades.

Are you using Outlook for email by any chance?

Run CheckDisc: http://support.microsoft.com/kb/315265

I know you are using Ccleaner, and that will clean out all the cookies, etc....weird...have you updated it recently?

Also - go to malwarebytes.org and download the free version. Scan with that and it will get all the bad guys!