[Vector Moore]

try this delete the launcherdata folder on mydocs/assetto corsa
If you have offline stuff you want to keep back that folder up.

If that doesn't work, steam integrity file check.

I removed the launcherdata folder, which removed the login-informations for srs login. When I clicked on the SRS Button in AC, the login-box appeared. After I typed my name and password it logged me in and the freeze appeared again.

Steam integrity file check done, but didn't solved the problem. Still freeze.

I uninstalled assetto corsa, deleted the whole assettocorsa folder from "steamapps/common" and deleted the remained files in mydocuments.
After that i reinstalled a fresh Assetto Corsa without using any save-backups. Installed the srs mod, and tried to log in. It freezed... 

I checked my firewall settings. Assetto Corsa is allowed in any firewall settings.

Honestly I dont know any more what to do. I just can say, that on the first day, after I installed the srs mod on AC the menu worked without any freezes. With Kaspersky antivir and anything unchanged to now.
Some days later (And I honestly didnt do any changes on my computer :/ I just installed my new fanatec wheel ) I looked again into the game to see which races are in queue. And yeah, it freezed.

Edit: 
The Interface works absolutely fine without any freezes, when I'm not logged in (see attached screenshot)