Version: Normal - 1.12 (I have the 1.12.4 maps downloaded)
OS - Windows 10
It came up with "Lost Connection to RA3" while on the Main Menu screen, then when I tried to log back in the game crashed.
This has happened twice recently and it hadn't happened prior to maybe a week or so ago.
I don't know if they'll be particularly helpful, but I've attached the .wer files (as .txt) that were created as well as the CNCOnline_Log.