Hi Jim,
thanks for your quick response!
I've investigated and tried all this and more (created arbitrary text files in the mentioned folders, started VIPM setup with admin account explicitely, disabled virus tool etc.) yesterday, it didn't bring any further info or success. But... a new day, a new game, and now the installation finished without any problem. Pretty weird.
Maybe there was some other software running in the background or it was LV 8.6 I've started (and terminated) before running the installer or something like this?!
Anyway, thanks for the free VIPM Community Ed