TeamViewer often runs fine without any issues for long periods of time when multiple computers are assigned to the same account. However, it will occasionally decide to change whatever is in the password field, preventing TV from logging in making the machine unreachable. If I reenter my password and sign in, it all returns to normal. It is not consistent when this happens, sometimes after reboots, some times after just leaving it running for a while.
When it does happen, I often have to add the computer again by assigning it to my account, and enabled easy access. This results in an old machine record which is not logged in, and just needs to be deleted.