Originally Trend ServerProtect nomal servers(one NT 4.0 SP6 and one 2000 SP4) lost connection to its central infromation server. Couldn't fix that so I uninstalled Trend on normal servers and tried to reinstall it. The installation always hang so I decided to have a look at Windows Installer Service. The service was set to Manual as default but I couldn't start the service. Realize it became a Windows Installer Service issue, I refered to many Microsoft Doco to try to reinstall the service. I tried reboot the server a few times, un-register and re-register the service under safe mode and normal mode, copied the fresh installed Windows Installer 2.0 files to the problem machine to overwrite the existing files. None worked. Now I cannot see the Windows Installer Service from the system service list. Anyone could give me some idea about recover corrupted Windows Installer Service?

Originally Trend ServerProtect nomal servers(one NT 4.0 SP6 and one 2000 SP4) lost connection to its central infromation server. Couldn't fix that so I uninstalled Trend on normal servers and tried to reinstall it. The installation always hang so I decided to have a look at Windows Installer Service. The service was set to Manual as default but I couldn't start the service. Realize it became a Windows Installer Service issue, I refered to many Microsoft Doco to try to reinstall the service. I tried reboot the server a few times, un-register and re-register the service under safe mode and normal mode, copied the fresh installed Windows Installer 2.0 files to the problem machine to overwrite the existing files. None worked. Now I cannot see the Windows Installer Service from the system service list. Anyone could give me some idea about recover corrupted Windows Installer Service?

Unfortunately, like with earlier versions of Windows, you're probably required to reformat the HDD then reinstall Windows. Because there's a good chance that the "repair" install feature won't work or work properly. It also may demand a password that you didn't put in, thus being locked out of the "repair" install feature. Sorry.

Oh My GOD!!!Then that's very serious problem now. The NT is our Notes server and 2000 is our Database server. It gonna takes ages to put all the stuff back-__-.Please tell me no...

Is the service not listed in the services control panel applet? What exactly did you do in your troubleshooting?

At first the anti virus software won't install, so we looked at the windows installer service. It is set mannual as system default. To do a test, we click start to mannually start the service. The service didn't start and it hang. Since then, We did most of things according to this refence

http://support.microsoft.com/kb/555175/en-us

Nothing helped and after we mess around with windows installer files, it is just gone from the services control panel applet. Now we are stuck and don't know what's the next

I would strongly suggest doing sfc /scannow from the command prompt, and if that doesn't work, do a repair installation. If the steps in the KB article didn't work, you likely have modified or corrupt (or at this point, missing) system files relating to the Windows Installer engine.

Thanks guys for your help. Eventually we solved the problem. This is how we did it.

The lastest error we got is "Service Database IS Currently Locked" when we double click any service from the service manager. Windows Installer Service is not in the list. We run command line "winmsd.exe" to find out why. There is a UPS service "APC manager" playing up. All the services state suppose to be either Started or Stop except that APC Manager. It is under Stopping state. We change its registry entry

HKLM\system\currentcontrolset\services\service name\start, type 0x4 in the data box to change the start up type to disable. Restart the computer. After restart, we can access the Services with no trouble. We run the Windows Installer again and it came out under the service. It's working again and we were be able to install the AV.

If you have an old (1.3 or older) version of APC PowerChute on the box, this is actually a known issue. Their certificate expired, and it causes all sorts of problems - either stop the service (which isn't wise if you are actually using it, but it works), or upgrade the software. Not sure if you're in this boat or not, but I thought I'd throw it out there.

Lucky that we are not using that APC software. However don't why somehow it was sitting in the service list.

See http://www.errorexpert.com/ - this may help.