If you don't have any anti-virus or anti-spyware programs you can use an online scanner from Trend Micro, called House Call.
Or, you can download a free 30 day trial of Trend Micro Internet Security (PC-cillin), install and update it, then let it scan for and remove all threats it finds, rebooting as instructed.
Right click, one at a time, on each of the five master HKEY names, then choose "Permissions." Find your administrator-level user name in the list of users and make sure that when highlighted it shows "Full control" under , in the "Permissions for " options field.
If it shows less than full control - try checking the box labeled "Full control" (under Allow) and click Apply.
Access Denied errors during a service pack upgrade are mainly caused by insufficient user privileges, either for overwriting system files, or the Windows Registry, or both.
What may have happened is that operating system files and folders, and/or branches of the Windows Registry have been assigned to "" account you are using.
At some point during the upgrade process it halts and a message box appears - telling you the following bad news.When the logon box appears type the user name: Administrator and then type in any password you have assigned to that account.If you have not created a password for Administrator, leave the password field blank and press Enter, to logon.Upgrading to SP3 must be done from within a full Administrator level account, infection.You should scan your computer with all of the security applications you have installed on the computer, after updating them to the current definitions.