If you search the forum for "Actual Window Manager", there are threads about various weird problems it causes going back to 2009.
We've also found that disabling or adding exclusions for similar tools isn't always enough, as their hooks and DLLs remain in the process. (They don't do as much, but can still go wrong. Don't know if that applies to AWM specifically but have seen it with similar tools.)
Re the freeze, it may still be AWM or could be something else. Please make some snapshots and send them to us when Opus is in that state: