I believe Mono is the achilles' heel, perhaps its memory management. Suspending or hibernating the system seem to make freezes or zombie processes more likely.
I have experienced a couple of hard freezes but those were during busy development period. Since then I've had zombie processes that effectively lock up Eddie, but they can be manually killed with "kill -9 <process-id>" or "htop", but for some reason not with "killall <name>".
Installing/launching htop, hitting F4 (for filter) and typing "eddie" is an easy to way to view the processes spawned in the Mono jungle.
Eddie is a nice GUI tool for managing the connection and one reason that initially attracted me to AirVPN, besides their sensible policies. Using Mono made sense for them, but the long-term objective has been to move to a native toolkit