There's a new Public beta to start and then you can try downloading the New 3.50 Release of Plus! (Might help because it's completely compatable with all versions of 7.0) if you get the same problems just post back here.
Some of the other posters here might correct me if I'm wrong, but if it takes 4-5 minutes to pop up, try uninstalling and reinstalling Messenger or Upgrade
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