question: if you don't see the ASIO drivers, how can you change buffer size then?
more questions: how do you feed MIDI, i.e. is there a sequencer installed on the machine?
if yes, please double check you don't have any MIDI or audio loops configured.
please make sure the mbox is NOT set as default audio device in windows (control panel, audio settings) - the mbox drivers are not multi-client, so any other application configured for the mbox will prevent MIR from accessing them.
driver & firmware version? vista SP1?
christian
and remember: only a CRAY can run an endless loop in just three seconds.