Has anyone any ideas what could be wrong?
Sounds like the the location for writing is not accessible.
The ini files are not writing and getting saved.
I would reinstall after turning off the Anti Virus just to be sure, but pay particular attention to the locations proposed by the installer.
The installer remembers the last install parameters so if you changed some location even by accident, it stays changed.
So see the attached and try to make yours about the same.
You didn't say if your Windows was 32 or 64 bit.
So give it a try
Fred