ok first off before you think Freelancer isnt compatible with windows 7 64 bit, its 100% compatible in most cases( I have it installed on two computers both with windows 7 64 bit, runs just fine. )

have you tried reinstalling? Could be a corrupt installation, even is you just installed reinstall in the following order…

uninstall all mods
uninstall FLMM
install freelancer
install FLMM 1.4

disable UAC(User Account Control)
Always run as admin
maybe set compatibility options for freelancer disabling visual themes(windows aero)
compatibility for windows 2000 or xp sp2 might work

What mods have you tried? Also is this a legit version of windows 7 64 or a “special” version
And is it windows 7 basic, home premium, professional, or ultimate?
And how long have you had it?

And is this a legit version of Freelancer or a torrented version, if its torrented try downloading another torrent of it.

If you are still having problems post your hardware information that would help a lot too, example 2-4 video cards in SLi or Crossfire might cause problems with freelancer.

Also what anti-virus and firewall are you using?

Also in rare cases with windows 7, its security will not give the your user account ownership of everything you install, there is a registry “hack” that allows you to take ownership of everything, if only I could remember where to find it( its been a while )

Also try different versions of FLMM there are 3 good ones available right now: 1.3, 1.44 beta, and 1.51 beta
Hope you get it working 🙂