Just did a fresh install of PTHD on a MacBook Pro and seeing the same crash in Structure Free.
Fresh install of Mac OS 10.8.3 and Avid_Virtual_Instruments_10_3_Installer_77520 and Pro_Tools_10_3_4_Installer_78970.
Loaded up an existing project, opened Structure Free, went to the browser, and spinning ball of doom!.
Thanks to the tip above I fixed the problem by unplugging the network and turning off the airport.
Now I opened the session and opened the plugin and went to the browser without a crash, navigated around. Then quit PT, plugged the network back in and turned on the airport. Re-open the session and now no crash because the browser is still in the folder where I left it last time (even though I didn't save the session).
So, this seems to affect you only if you have a fresh install and have never navigated around the structure browser and have network plugged in?!
