Try to install
Your current version of Windows is not supported. Check the system requirements for supported operating systems and required service Packs.
What to do for it
I' using Win 7 - 64 Bit (Ultimate)
Windows 7 is still supported for F-Secure SAFE.
Have you got all of the latest Windows updates installed?
Recently there was such topic about Windows 7:
and some topics for business-solutions:
Just like connect such topics between each others. Sounds that suggested 'Service Pack One' and all available latest updates for system should sort such trouble.
But good if you will back with feedback. What if there some other troubles with certain Windows 7. I tried with my own experience and looks like it was possible to install F-Secure solution.
Note that SP1 is also mandatory requirement for majority of recent Windows updates so not having it installed imposes a significant security risk