My .vbox is a Windows 7 install that works perfectly under VirtualBox, but won't open in Parallels. Like I said, even a basic .vbox file crashes when I try to load it with Parallels, so it seems like when parsing the .vbox file the app barfs, irrespective of the guest OS contents.
I've sent the crash log via the app, but I'm not holding my breath. I guess I'll stick with Virtualbox for now, especially since my only reason for switching back to Parallels was to try the retina support, which apparently is still iffy. It's nice to have choices. Thanks for the reply.