[Ti] ILLEGAL REQUEST...INCOMPATIBLE FORMAT

[Dr Trevor J. Hutley]

Al-Powerbook, OS X 10.4.2

I am making backups/archives of many of my files on to DVD using  
Roxio Toast 6 Titanium 611.

I made several this morning.

When I was making a backup of my eyeTV files, I got this error message:

         The drive reported an error:
         Sense Key = HARDWARE ERROR
         Sense Code = 0x03

then

         The drive reported an error:
         Sense Key = ILLEGAL REQUEST
         Sense CoDe = 0x30, 0x05
         CANNOT WRITE MEDIUM - INCOMPATIBLE FORMAT

about 90% of the way through writing the DVD.

It seems that 4.17 of the 4.2 Gb of files was in fact copied, and the  
DVD works fine.  There are perhaps a few files not copied.

Does anyone have any idea what these error codes mean, and their true  
significance?

I am using Imation DVD-R 8x but only burning at 1x.

This happened when I put another DVD in and repeated the burn, so it  
was not the DVD media (unless both are defective in the same way).
I then tried one DVD from the bottom of the spindle, to see if it is  
the same.  It was.  4 min 14' left to burn, same error message.

Next, I tried reducing the size of the DVD content to just 4.0 Gb,  
from 4,2.
No problem....

How do we explain that ?  Bug in Toast?

regards,  Trevor