Starting with the 5698 nightly build I have not been able to get any of the new nightly builds to work (5700 0r 5706). The launcher freezes if I try to select any of the new builds and fred 2 wll not work with any of the new builds. I tried renaming the exe files to drop the date and rev number. and replacing the old file with the new, both named fs2_open_3_6_11r_sse2 so I didn't have to select the new exe file. When I went to open the launcher I got a message saying there was no disk in drive D. Maybe this is a unique problem to windows 7 but I haven't had any problems with Rev. 5692 and previous.
Edit:
Never mind. I tried it today and it worked. Not sure why.