For a very long time, with Ps CS5 and CS4 whenever I would try to use Photomerge directly with raw files as input I would occasionally see Photoshop just crash out or quit without any message (maybe 1 in 4 times). So to increase chances of success I just got in the habit of exporting PSD files from Camera Raw, then running Photomerge on those PSD files. That worked well enough and wasn't much trouble.
But I consciously stopped doing this workaround with Photoshop CS6 during the beta, then with the release, and I'm happy to say that every one - every single one - of my panos made directly from raw files with Camera Raw 7 has been successful.
Whomever fixed it, however you fixed it - you DID fix it. Thank you!