Windows Installer can not be accessed.

I was browsing these forums looking for some help because I can not install any software that need windows installer to install. I found a few things nothing worked, but when I tried to install the windows installer clean up utility I got this error message "The Windows Installer Service could not be accessed. This can occur if you are running Windows in safe mode, or if the Windows Installer is not correctly installed. Contact your support personnel for assistance." I am not in safe mode, windows installer used to work, and I am trying to avoid calling Microsoft because I think at least few of us knows how much that will help.

I am using Windows XP Pro, Version 2002, Service Pack 2. I am running a HP/Compaq nw8000. Any help would be greatly appreciated.

Follow the guidance of NooNoo in this earlier thread - if that doesn't help some others have offered some useful insights.

http://forums.windrivers.com/showthread.php?t=77401

I had one of thosed today turned out the registry hive for root was missing permissions. It had only everyone with read permissions. Added administrators and system with fill control and it worked right away.

One thing to try first is to register these dll's
Start then run and enter each of these hitting OK after.

regsvr32 wuapi.dll
regsvr32 wuaueng.dll
regsvr32 wuaueng1.dll
regsvr32 wucltui.dll
regsvr32 wups.dll
regsvr32 wups2.dll
regsvr32 wuweb.dll
regsvr32 wuweb.dll
regsvr32 atl.dll
regsvr32 wuapi.dll