This usually happens when a service that is required, the Trusted Installer is not running. Follow the instructions below to repair this.
- Click Start
- Click Run
- Type: services.msc > Press Enter
- You should be greeted with a Services dialog list look for TrustedInstaller.
- Right click TrustedInstaller and click Properties
- Set the TrustedInstaller service to Automatic and click Start
- Attempt Service Pack installation again.