I would start scanning with your anti-virus scanner and also download, install, update, and run full scans with the free versions of Malwarebytes Anti-malware and SUPERAntiSpyware.
Several days ago web pages started down loading very slowly. It doesn't matter what web browser or search engine I use and my upload and download speeds are fine so I tried system restore but I get an error message it can't complete system restore. I tried several different restore dates and none will work. I have not installed any new software or hardware in the last month. I'm using Win 7 64bit.