Windows Installer service

Hi,
I have a real problem with my XP and I’ll use any help.

I can’t star the Windows Installer service so I can’t install or uninstall a lot of programs.
“Error 5: Access is denied.” is the message when starting it manually.
In the Event Viewer (Application) is this warning.

Event Type: Warning
Event Source: MsiInstaller
Event Category: None
Event ID: 1015
Date: 11-May-06
Time: 2:20:17 AM
User: COMPUTERGordan
Computer: COMPUTER
Description:
Failed to connect to server. Error: 0x80070005

I started almost all the services (I was thinking that this service is dependent to other services) but the message was the same. No viruses or spyware (scand with "Ad-aware","Spybot" and "Zone Alarm" ). I’m also logged as Administrator.

Any thoughts :?:[b][/b][b][/b]

Yes, the server is started automatically. The files for the W.I. are at the right place in system32 directory, and the registry for those files is correct. Maybe if I replace them with other good files. Also, I have maid some changes with “Advanced Windows Care” utility. I’ll try to restore, but there is a significant improvement with these tweaks.