I'm re-posting this from a reply I made under the Toast 7 forum...
I'm running Toast 8.0.3 on a Dual 2 GHz PowerMac G5 with 2.5 GB of RAM under OS X 10.4.11
I've burned several DVD's and the symptoms are the same for all of them:
After burning and verifying successfully, I am asked if I'd like to Mount or Eject the DVD.
If I choose Mount, the disk loads successfully (I can see it in the Finder under my "Computer" directory with all of my other drives). Not only that, I am able to use whatever software I like to view it. Once I eject the DVD, I can no longer get it to mount on my computer. It doesn't matter what software is running at the time, or if no software is running, the DVD won't mount. After about 3 or 4 seconds of VERY quiet searching, the disk spins up to speed for about 45 seconds or so, before "spinning down" and failing to mount (there is no message of any kind from the system that there was a problem reading the disk). In fact, the disk doesn't even show up in the Disk Utility at this point. I can mount and view a DVD that was burned on another computer, or a "factory" DVD movie that I either purchased or rented. Also, I can take any of the DVD's that I burned on my computer (the ones that won't mount) and view them successfully with the low-end Sony DVD player connected to my TV.
This problem only seems to occur when burning DVD's. I don't have any issues with music or data CD's mounting.
I've scoured the internet and have yet to find a solution to this problem.
WHY HAVE WE NOT HEARD FROM ROXIO ABOUT THIS PROBLEM!!!!!