Where do you have your Brain files stored? Your local hard drive or cloud storage like DropBox, Google Drive, etc.?
On the machine that is having trouble, please try this:
1. Close TheBrain application and Navigate to (C:\Users\USERNAME\AppData\Roaming) on your machine.
2. Delete any (PersonalBrain) folder if one exists and you are no longer using or no longer have PersonalBrain 6 or lower installed.
3. Open any (TheBrain) folder and delete both preference files: (TheBrain7Preferences.bak) and (TheBrain7Preferences.xml)
**Please note that doing this will reset TheBrain preferences and you will need to login to TheBrain application and manually open your Brains: File > Open Brain... to re-populate the Brains list.
Once these steps have been completed please try restarting TheBrain.