I understand 3.7.2 is the latest version that includes scrypt mining?
I've also tried 3.5.1 and 3.1.1, none of which seem to stop the issue. It's happening on multiple pools as well.
EDIT: I'm now using CGWatcher to restart the miner when the hang occurs. However, when it is restarted my voltages seem to reset. It kept the clock settings this time though and resumed mining at the expected hash rate.
It might also be relevant that when the new miner process appears, the temp and fan rpm monitor in CGMiner are missing.