I decided to double check the defect sequence, and see if it is reproducable. It is! The EXACT SEQUENCE is:
1) From webmatrix, start a brand new Orchard installation.
2) Install the themes "metal" and "minty", set "minty" as the theme, then set "metal" as the theme.
3) Install Vandelay industries
4) Establish a theme picker rule (with select rule "MSIE") which selects theme "Minty"
5) Test the site on both IE9 and Chrome - confirm that the theme picker is performing as expected.
6) Install the "designer tools" module.
7) Confirm that Orchard site in Chrome is still working.
8) Try to confirm that Orchard site is IE9 is still working - EXPLODE!!!! IIS Express goes belly up!
In short, I'm guessing there is some strange incompatability between the shape tracer and the "Vandelay industries" theme picker. Restarting IIS Express or restarting webmatrix only gives me a chance to view the site in Chrome again. The
moment I go to IE9, it explodes all over again. If I use Chrome to disable the "Theme picker" feature, then IE9 is fine - and no longer causes IIS Express to explode.
Comments on the above sequence:
#2: setting both themes seems to be necessary so that Vandelay's "theme picker" can "see" the Minty theme.
#: During this whole sequence, I am logged in to Orchard as admin.