I now understand now that Toast rewrites the .plst file every time you open it. However, I'm still have the same issue with Toast not knowing the correct disc capacity of a standart Blu Ray Disc. Every time I try it Toast keeps saying the disc capacity is only 19.6MB. I reached Roxio tech support and they said to do the same thing: quit Toast, delete the .plst file, and try again. Still no luck, same issue.
I'm on the most current version of Toast, 11.2 build 3175. I'm trying it on both my iMac with 10.8 and my Powerbook with 10.6. This program seriously just doesn't seem to work to make a standard Blu Ray disc.