After you install SP3, trying to start a Microsoft Office program generates:
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.
This behavior can be caused if the SYSTEM account does NOT have Full Control permissions on the folder that Windows Installer is trying to access AND / OR if the DCOM default impersonation level is set to Anonymous.
If the problem is the SYSTEM account permission1. Open Windows Explorer.
2. Select the drive root and press Properties.
3. Select the Security tab.
4. If the SYSTEM account is listed, skip to step 6.
5. Press the Add button, select the SYSTEM account, press Add, and OK.
6. Check the Full Control box in the Allow column and press OK.
If the problem is the DCOM default impersonation level1. Open a CMD prompt and type dcomcnfg.
2. Select the Default Properties tab.
3. Press Identify in the Default Impersonation Level drop-down list.
4. Press OK.
ren %windir%\system32\missip.dll missip.old
6. Re-install Windows 2000 SP3.