Would this "bug" be guaranteed to occur each time someone burns a 70 minute project first in standard definition to a DVD-SL and then in AVCHD to a DVD-DL or a BD-RE?

 This could be precisely the reason why I've never been able to burn longer high definition projects to DVD-DL or BD.  I always burn in standard definition first, and the size is commpatible with a 4.7 GB DVD-SL, since that is the format which most viewers need.  However, when I next try to burn the same project in HD, which increases the space use well over 4.7 GB, the "disk full" message appears immediately.    What drove me nuts was the fact that I could burn the big AVCHD disk image to hard drive, but not get Studio to burn it to DVD-DL or BD.  I gave up entirely, assuming that it meant Studio simply would not burn AVCHD to media over 4.7 GB.

Does the manual solution you mention involve deleting items from a generic "disk burn" folder, or from a project-specific folder?  Is it useless use the general command to purge the auxiliary files?  I am a bit timid about poking around and zapping obscure files unless they have a definite name or ID.  I fear disabling the software altogether.

 Voxmagna: could you please give a screenshot of the location and nomenclature of the culprit files?

Meanwhile, I will try to burn a project first in HD before burning the SD version, to see if this allows me to break the 4.7GB barrier and burn to DVD-DL or BD.

Pinnacle ought to patch this problem, and it should not be hard.  Otherwise, it will bedevil others, sooner or later.