PS., the link to the MediaLab probe task samples and documentation can be found here:
http://www.empirisoft.com/support/showthread.php?t=375
Additionally, if you search on "probe" here in the forums, you can find additional postings some of which contains troubleshooting experiences with other users conducting these types of experiments. In fact, I just went through some of them and notice there was at least one Windows Vista related issue--are you running this on XP Vista or Windows 7?
Blair