RE: Windows Installer Error
You can check the below article that can fix your issue:
Error message when you try to add or remove a program on a computer that is running Windows XP or Windows Server 2003: "The Windows Installer service could not be accessed"
http://support.microsoft.com/kb/315346
"The Windows Installer Service Could Not Be Accessed" error message when you install a program in Windows XP
http://support.microsoft.com/kb/315353
"Windows Installer Service could not be accessed" error message when installing application
http://support.microsoft.com/kb/319624
Re: Windows Installer Error
You can simply use a Dial a fix and then run it and choose "Windows Installer", and after some time it will start to work.
Re: Windows Installer Error
So I did a system restore back the some day before i installed SP3 and the issue seems to have gone. Thanks for the replies.