Share to Blu-ray

I have searched the fora and still cannot find the answer.
I am unable to Share to Blu-ray any video longer than several minutes.
Short clips, 1:35, burn ok with the template menu, etc.
Longer clips, 27 minutes, elicit an error message about unable to burn to this disk.
Fresh, name brand stock.

MacPro OSX 10.6.1
FCP 7.0
5GB ram
External burner Buffalo (Pioneer)

(I have attempted Toast 10 with mixed results: menus that play on a Sony 300 but not on a 360 and vice versa, content that plays 4:3 on the 300 but 16:9 on the 360.)

Your thoughts and counsel, please.

I have posted an issue regarding creating an AVCHD disk using the superdrive (red laser). I had no problem burning a 6 minute project but haven't had any luck creating anything longer either.

I was hoping to use these as check disks before burning real Blu-rays.

I keep getting a quicktime error.

Have you tried creating a disk image (exporting from) Compressor? Also is this a recent development? I'm wondering if Apple recently broke something in quicktime and passed it along in software update?