prob Burning disk images

ok i got a mac mini 1.83Ghz 2GB of ram and a MATSHITA DVD-R UJ-846 as my Superdrive. Ok well recently i have tried burning some ISO Nrg Dmg and other such formats had no problems. Until i tried to burn a DL DVD i could never get the disk completely readable it would start up then freeze or wouldnt be readable at all. so i thought maybe it's something with the firmware. so iupgrade the firmware. now i can't burn any type of Disk image. is there a way to retro flash the firmware maybe. or is there something i can check to see what the prob might be.

thanks in advance for any help provided

Can you play dual layer DVD's still? Also, check check the permissions on your /dev directories to make sure nothing was changed and the drives are still R/W. Just a thought.
-Dave

how do i check the permissions?
not sure if i can play DL dvd's as it was a game i was backing up. I mean i can still read the disk. i just can't copy from any disk image and just found i can't even copy from the original disk either DL or not. when i do try this is the message i get from toast 8.0:

The drive reported and error:
Sense key = MEDIUM ERROR
Sense Code = 0x11
UNRECORVERABLE READ ERROR


now thats the message from the superdrive i also have a Lacie External that will burn the disk images and Disk but they are not readable. i had also updated it firmware when i was trying to do that DL disk. Both the Superdrive and the Lacie were working fine. I've even tried reinstalling OSX from Scratch and still get same probs. and insight or help would be greatly appreciated.