generation hangs while truncating tables due to suspended spids in db.

Hey, data generation hangs due to a few suspended 'SELECT' spids left over in the db. If i kill the offending spids and re-run the job, everything is fine. The trigger seems to be related to the data preview, ie., if i click around on a bunch of cols in the tool, i see these spids showing up and they never clear.  This started happening after i included a foreign key generator, although it's not obvious to me why.  If i turn off auto-preview (and never manually activate it) everything's fine. I kinda need preview though.