Reverting @7de28f8f1dbfdf39a810800b841b0df49f02aac6. You need the locking
when running on .NET 4+. Everything became thread UNSAFE between .NET 3.5
and 4. 3.5 docu:
http://msdn.microsoft.com/en-us/library/system.messaging.messagequeue(v=vs.90).aspx
vs 4 docu: http://msdn.microsoft.com/en-us/library/system.messaging.messagequeue(v=vs.100).aspx
Bad call, andreasohlund! :)