G'day Rikki,
quite some time ago I had the same problem with an HP notebook and Vista (Win7 shares the same kernel). The problem turned out to be another process trying to share the audio device.

Make sure there are no applications trying to use the "MicroSoft GS Wavetable Synth" as a MIDI output device as Vista/Win7 assigns the audio to it immediately. This was my problem. In my case I was experimenting with "VSTHost" which had activated the M$ synth.

IIRC it was necessary to disable UAC in order to install correctly too.


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