I have listed the most obvious reasons why a computer may be running slow, some of which you may have already tried but for completeness they are mentioned here. As a reminder, if you are using a laptop it will be running slower on the battery as opposed to running on the mains power. First of all make sure you do not have any viruses or spyware. Run your anti virus and anti spyware programs in order to clear out any beasts. Spyware is becoming more and more of a problem because some spyware is extremely difficult to identify and even more difficult to remove. If you do not have any protection these applications are exceptional and available for free download: Anti spyware: http://www.superantispyware.com/ http://filehippo.com/download_spybot_sea… Anti virus: http://www.avast.com