This is the classic symptom of a firewall problem. When you click 'start' it is the first time your comp tries to access the game server (as opposed to the update server.) That access is being blocked, and the most common source is your firewall.
Often, the weekly maintenence causes firewalls to view the game as a 'new' application, and block it. I have to manually re-authorize all the lineage programs when updates occur. Try to open your firewall control and reauthorise the game programs..
Ditto on the firewall thing. Also, you may want to try using the 'full check' option in case a file got corrupted on dl and the program didn't catch it.