At the risk of sounding stupid, and I risk that every breathing minute, isn't there something in that error about region code? Have you reset the region code or tried to do so? I say this because I think that you were having trouble playing movies from Central or South America and there may have been some loose talk (some of it mine) about websites that talk about resetting the region code software. Even if you haven't reset the region code actively then apparently you could do it by trying to view a video from another region:
QUOTE
In Mac OS X 10.3 Panther and later, users with administrative privileges aren't prompted to change the region the very first time a DVD-Video disc of a single region is inserted. Instead, the region of the DVD drive is automatically set to the region of the DVD disc that was inserted. Accounts that don't have administrative privileges must authenticate with an administrator account name and password, because changing the drive's region code requires administrative privileges.
That's from this page at Apple:
http://docs.info.apple.com/article.html?artnum=60183I'm assuming from something I read here or elsewhere that Apple is still adhering to this region limitation scheme and that you are blocked from changing zones more than 5 times without extraordinary means (meaning reflashing the DVD drive).
Later: Another thought is that the message is telling you something is wrong with the DVD drive itself. I'm sure this must still be in warranty so maybe you can go visit the genius bar!