yep, this may happen after a dc when the client displays an incorrect screen. However, it's only a display issue and you may not have to restart the whole game to continue...
Try this first:
1. Select a shipyard where you have some ships (screen will just flash and nothing else)
2. Press the Battle button next to the Shipyard one
3. You can now continue playing as normal - everything will start to work again (you can join a battle or go to any shipyard or whatever you feel like and it will work)
Note: In step1 in your selected shipyard, the first ship in the order must able to clear the port (have BO), else this will not work and afaik you cannot switch ships while in the bug.
Hope this helps :P
