After a few weeks of frustration I finally found the solution for my problem.
My Windows Mobile device name kept changing into HTCXX, where the XX were numbers. I blamed Active Sync, my bluetooth car kit, the phone itself. But eventually it was me. 
It seems that when you have an underscore in your device name, Active Sync changes that into something random.
Solution: don’t use a underscore in your device name…!
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