Chances are the computer might be running Trend Micro or some other type of anti-virus / firewall application. In my case it was Trend Micro that was not only blocking me from installing Office 2010, but was also blocking me from installing Windows XP Service Pack 3.

You can simply unload trend micro or stop your anti-virus application and then retry and it should work great. If you have problems still you might want to try to boot into safe mode and scan your computer throughly or make sure some other application isn’t blocking access.