I follow all the instructions from the "Radar Contact Version 4 Key" mail, I started RCv4 as administrator and finally installed FSUIPC 4 but the problem keeps. The issue is that when I enter the key into the space and click "Done", the app freezes and appears "Not Responding", then it closes and when I re-open RCv4 the registration windows appears again and again.
I have also read AVSIM and it seems that several people had also this problem, but magically it was solved.
Can someone help me? I tried everything I can but nothing happens.