Doug Hennig has been working with the problem.

As it stands now, with the CM Dev Env instantiated (and with SFQuery/SFReports in the app's project), the SDT Database Explorer will load ok, but will not show any of the files in the .dbc.

With the CM Dev Env unloaded, it works just fine. Dave Lehr has tested it with current versions of CM (but without SFQuery/SFReports) and he reports all is working well.