HELP! Install service doesn’t work

OS windows 2000 pro totally updated.
When I try to install an *.msi program I get the error messgge: “The Windows Installer Service could not be accessed. …” Start/run/msiexec returns that version 3.01.4000.1823 is installed.
msi.dll is version 3.1.4000.2435 and is properly situated in system32/ can anybody help?