Do a full scan with some antispyware software click here and the installed antivirus software, remove anything they find, then disable the antivirus software before running the system restore (disconnect from the internet while your AV software is disabled).
The error message indicates a problem with MyWebSearch which is an ad-serving app that comes bundled with some software. Its not actually malicious but better off removed. Perhaps the AV software removed it already, or is preventing the system-restore occuring because it's treating that file as an infection. click here