Well I can tell you that Windows 7 isn't causing you the problem cause thats what I have. And I just botted a rouge last night.
If you just installed Hb and the frameworks I would try restarting your computer.
This sounds exactly more like the problem im having now. Always get that spam message that the key couldn't be found. Got a fresh install of everything, aswell as wow (no addons), .net framerate 3.5 Eng. (did full cleanup before ofc). But still, my warlock just stands there staring at the mob, and after a few he blacklists the mob and heads for a new mob... then repeats the blacklisting (add infinitum). But yah... there's something with the "mscorlib"... Worked perfectly a few days ago untill i reinstalled everything.