Install Service Pack
Here is steps to install a service pack for your operating system
- 
				Go to Microsoft's website and download the service pack. (Choose the distribution version. It will give you the full package. Download it and burn it to a CD or a flash drive that is external to the computer) (If you already downloaded the service pack, skip to step 2) 
- 
				Turn off System Restore 
- 
				Run an anti-virus program (make sure it has all the updates) 
- 
				Run two or more anti-spyware programs (Make sure they have all the updates) 
- 
				Here is some good anti-spyware programs (there is more good ones beside these) 
- 
				Malwarebytes from http://www.malwarebytes.org 
- 
				Spybot from http://www.safer-networking.org 
- 
				Re-enable system restore 
- 
				Create a system restore point 
- 
				Limit MSCONFIG (this includes disabling your anti-virus) 
- 
				Run the service pack install that you downloaded. 
- 
				If it still will not install, try allowing windows update to install it. 
- 
				Use the Spyware and Virus Troubleshooter for further scanning of the system 
- 
				Use the Software Troubleshooter 
When you get the service pack installed, return to step 7 but this time return MSCONFIG back to the original setting. Be sure to do all the updates afterwards
