Can't do multi user install of creator(+library) on WinXP (32bit)

I am not sure how to categorize this exactly.
I have already something written up in this thread:
https://qt-project.org/forums/viewthread/32179
To summarize it:
When I install the creator via the combined lib+creator installer (tried: Qt5.1.1 offline/online MSVC 2010 OpenGL/MinGW) I get no option to install it for all users of the system.
When browsing to the .exe in the bin folder and starting it manually as non administrator the creator starts and then hangs indefinitely.

When the creator is installed with the dedicated installer (without the libs) there is also no choice to install for multiple users, which means again no desktop/startmenu entry and no file association for other than the installing user, however, I am now able to start the creator via executing the .exe in the bin folder and this time it is working (say, no hangs).