Reason might be a corrupted header in an email that was sent to you. Delete the emails that you dont care for. Also this might be generated by an antivirus or firewall. Try disabling them. If non worked download and install cleanup and run. Log off/in when prompted. ( Remember cleanup! doesnt do backups. If you have files in temp folders which are important or programs make sure you move them first ) If still no hope you might need to chase for malware. Click on greyknights linik below and follow the steps.