problem is solved

observation
- installer problem only occurred on win7 32 bit with prior python installation
(my working system)
- When repeating the installer problem I noticed that a window was opened very shortly with python.exe running. An error message from this call resulted in the exit process of the installer
- the window popped up only for about 1second. A was reading (taking a video) that it was complaining about an error in numpy when calling imp.py in /python33/lib (the old installation, something wrong with libtool, bootstrap)
- I removed step by step all installed libraries, but the error still appeared
- I removed the prior python 3.3.5 installation completely, now the installer worked
- when opening the window with python, it was downloading something like setuptools (not absolutely sure about the name)
- a test with nose 1.3.3, numpy 1.8.1, scipy 0.14.0 (all from Gohlkes web site) went ok.
- unfortunately, the error message with the registry was not reflecting the problem

Hence, the solution is to remove the prior installation of python. That was not necessary in older versions and not necessary for win7 64 bit: strange.