SENSE KEY = MEDIUM ERROR 0X73, 0x03 this is getting rediculous---

Seems unusual in a new machine, but try a lens cleaning disc - get them from most electronics stores - just a DVD with some brushes stuck on that cleans the laser head in the drive as it spins. In the past the sense key error has indicated fluff or dirt on the lens, but there's no guarantee this is what your issue actually is! Sorry!

I have the exact same issue with my 10 month old Mac Pro. I've burned several spindles of various brands of DVD-Rs without ANY issues, until a few weeks ago when I upgraded from Tiger to Leopard. Now, both of my drives spit out coaster after coaster. I was halfway through a spindle that burned fine in Tiger, now none of them work, so I'm skeptical it is a media issue. The fact that both identical (OPTIARC) drives were working fine in Tiger, then simultaneously stopped burning immediately after the Leopard upgrade is way too much of a coincidence for me.

I see on here that I'm not the only one having this issue. I've tried some of the suggestions on here: safe boot and install the 10.5.3 combo updater, reset pram, a clean OS install on a separate drive, disk util and defrag, etc., but nothing works. I have not used a cleaner on them yet, but I would bet good money that's not the problem. My next step is to try to reset the SMU, then my last resort is cleaning. I'll post back the results, but if anyone has solved this, please chime in...

ME TOO. YEARS of burning dual layer dvds with no problems, wide variety of media, after doing a combo upgrade to latest 10.5.4, dual layer dvds cannot be burned. Sense key errors every time. And mind you this is 2 different macs, built in superdrive on one, external burner on other. Every DL is a coaster. HAD to be the most recent upgrade; media works just dandy at work where i have an old machine running 10.4.2

I have the same issues. Everything was fine in OS 10.3.9 but not since I updated to 10.5.4

I use the original DVD burner that came in the computer which I had to flash with Pioneer DVR-108 firmware to be able to use the DL capabilities (thats a whole other story) also using Patchburn 3.1.7

I've never had a problem till after my recent OS update to 10.5.4 Now I have ...
(Power calibration area error 0x73,0x03 with DVDSP 3.0.2 and Sense Key = Medium error Sense Code = 0x73,0x03 with Toast 7). I did knock out one dvd copy of a DVDSP master in toast before getting the error code on the second copy.

I'm going to switch the 108 into my G4DP 800 and try burning with the same burner and apps in the 10.3.9 environment to see if i get any of the same error messages.

So far I think OS 10.5 might be the issue?

ok, so I moved the DVR-108 into the G4DP 800 running OS 10.3.9 and ran the toast test and got one clean burn before doing the second and got the same error code.

I put the DVR-108 back in the G5 and ran a lens cleaner over it and burned a master out of DVDSP 3.0.2, no problem, knocked a copy out on toast 7 with no problem until I tried doing a second copy in toast at which I got the error code again.

I then switched in an LG burner and did all the same tests and had no problems at all.
So I guess my Pioneer DVR-108 that came with the G5 is stuffed and I need a new burner.

Cheers

Perhaps you will try this very strange solution (it solved my problem, but its a really strange way...) http://forums.macosxhints.com/showthread.php?t=77414

TOAST IS DAMAGING THE OPTICAL FOCUSING LENS STOP USING TOAST IT JUST FINISH DAMAGING MY SUPERDRIVE ALSO I JUST STARTED TO USE THIS SUPER DRIVE BECAUSE I DIDN´T WANT TO USE IT ON MY IMAC, SO I USE TO BURN DISK ON MY EXTERNAL DRIVE AND TODAY I DECIDED TO USE A DISK I HAD SAVE FROM PREVIOUS RECORDING WITH THIS SUPERDRIVE AND TODAY I JUST TESTED THAT TOAST DAMAGES YOUR DRIVE, IT IS PROVEN BECAUSE THIS SUPERDRIVE ONLY HAD BURN 3 DVD+DL DISK AND ONE I SAVED AND AFTER A MONTH AGAIN WITHOUT USING IT I FIND OUT THAT TOAST IS THE PROBLEM HERE

I cannot believe it, but I found this crazy fix posted in another Mac form and itworked for me:

Open System Preferences.
Click on "International"
Under "Languages": Drag any of the other languages to the top,
then drag English back to the top.
Set "Order for sorted lists" to English
Set "Word Break" to English (United States, computer)
Close System Preferences
Restart computer

Incredible! It works! I don't know why but it's at least worth a try.

See this topic http://discussions.apple.com/thread.jspa?messageID=7667550 and the reply from Kerrolin16 on May 3, 2008:

"I have a Macbook pro and using Toast 8. I use Memorex DVDs. What it is apparently is a preference issue with the software. When we went to the original environment the burning was fine. Thus, if you go through your user name and your harddrive library, preferences, what you need to do is delete any file containing the words roxio or toast and then delete the file: apple.finder.plist. These are plugged into several preference folders so you MUST find them all and delete them. After that shut down and restart. It has fixed my problems 3 times already although this last attempt was a little harder than the first two times because it was embedded deeper than before."

I would add that in my case, this was a Roxio Toast problem and not a hardware problem. Before I removed the Roxio software, I burned a CD (I only use Gold archival CD/DVDs) using the built-in system software and it went through perfectly.

Remove:

User > Library > Preferences > com.roxio.Toast.plist
User > Library > Preferences > com.apple.sidebarlists.plist
User > Library > Preferences > com.apple.finder.plist
User > Library > Preferences > Roxio Toast Prefs

Not only did I remove the Roxio preferences listed above, but I also removed Toast from the Applications folder and reinstalled it. I am using Toast 6 so this may not work for you.

Did you try "formating" the dvd +/- rw first?

Are you taking about a DVD-R or DVD-RW? +R +RW