found a solution by myself for this on the Internet:
http://www.pcbanter.net/showthread.php?t=758955
I reregistered the following dll's as to repair 'event system'
Register the following *.dll files.
Start | Run | Type or paste the following one at a time and hit your Enter
key. You should see a message telling if they registered or not.
regsvr32 comuid.dll
regsvr32 COMRes.dll
regsvr32 Comsvcs.dll (did not work here: "..no entry point found")
regsvr32 ole32.dll
regsvr32 oleaut32.dll
also my msi-installer is working again perfectly...:-)
NB: I did not try this on vista for there were other things to get managed with(shutdown, text-to-speech in german)
