The Toast 10.0.6 update DOES NOT fix my 'Interface error 5.....' problem using OS 10.6.2 and the internal GA11N (JA18 firmware) burner.
Using the OS 10.6.2 Disk Utility for a DMG produced by Toast 10.0.6 the GA11N works fine for DVD +/-R.
An external burner (OWC Mercury Pro) also works fine using Toast 10.0.6 and OS 10.6.2 for all DVD media that I have tried (Verbatim, TDK, Sony, Maxell).
iMac, 21.5 iMac, 3.06GHZ, 4GB, 1TB Mac OS X (10.6.2) External OWC Mercury Pro