I am having the same (or very similar) problem. I am also using Pro Tools, and Jam used to work fine, so maybe it is a Pro Tools update that broke it. I am also getting strange behavior from the Digi Core Audio app., in that I have selected built-in audio in the System Prefs, and Core Audio still launches occasionally.
Here's my problem: Mine crashes and freezes at the beginning of a CD burn or at the end of a Disk Image save. The screen freezes and I can't quit or even force quit the program. It looks like the CD's and Disk image are made, but I haven't tested them yet.
I tried several different disks and a couple of different Jam files with no luck. I did make a new Jam file with the same sound files as the one that was crashing (without changing the order, putting in the CD-Text, Mastering Info, or ISRC codes), and it worked fine. As soon as I changed the order, put in the exact pause lengths, the CD-Text, Mastering Info, and ISRC codes, it wouldn't burn without freezing.
I have to hold the button in on my computer to get it to shut down after these Jam freezes. NOT GOOD.
I am running Jam 6.0.3, Mac OS 10.4.8, G5 dual 2.0 gHz, Pro Tools 7.2
I realized that I had sucessfully burned some CD's a few days earlier with the same songs, but without the ISRC and UPC codes, so somehow those are what is making it freeze. Also, after a lot of testing, I was only able to get it working with an external FireWire CD burner. FYI: my internal drive that won't burn Jam CD's with the codes is a Sony DVD RW DW-Q28A (aka 16x Superdrive)
By the way, Toast works fine for me, but again, it doesn't record ISRC or UPC codes.