I have the same problem. It worked perfectly til two days ago. Turning UAC did not work. Any other suggestions? Because im going through withdrawl of the game...
Ensure that you have a firewall exclusion setup for STO, the file you're looking for will be titled "GameClient.exe" without the quotes. You can even test this out by simply disabling your firewall software, be it Windows Firewall or another 3rd party software.
Did you fully disable your firewall or just add an exclusion? You should try to disable the entire thing then test, at least that way you can fully rule out your firewall or find that it's the culprit. Also, how many different security software's are installed on your system? You should only have one installed as they love to butt heads if you have more than one and they do NOT function like you think they are. Just something to keep in mind. Keep on reposting here so we can work this out.
Wait.. I searched for GameClient.exe and nothing showed up.. this could be why its not working haha. But, everything is installed including the Star Trek Online game. It will let me sign in, and it will even patch, but it loads on the screen that says "Cryptic." . And dont suggest to reinstall it. Cause ive done that to. I use it with steam btw.
-edit: Scratch that. Its there . Ive set all my firewalls to let it work. Still.. nothing.. :/