Program fails to run

I just installed (and re-installed and re-booted) the Avogadro package on my
computer (Win 7, x-64, 4 GB RAM, INTEL Core i3 - with automatic update of
windows software). Also I am using dual screens with a Samsung wide screen
for my main screen and a Dell “normal” screen as my secondary screen.
Installation works fine - no reported problems.
Trying to launch the program is another matter - nothing, absolutely nothing
happens on the display(s)!
When trying to apply different compatability settings I sometimes get asked
to allow the program avogadro.exe the right to make changes to the system
(hard drive), but granting this does not help.
The HD-lamp flashes a little when launching, but nothing shows up on the
screen or in job list.

Are there any settings that I should be aware of or any other suggestions
for getting the program to work?

Knud Reffstrup