Cannot open disc: Code 81 with machined DVD-R's

[NuVigilance]

Hello
I'm trying to rip my SDTV shows contained on a Philips DVD-R made by a Panasonic DVD-Recorder to my external hard drive, which I run MakeMKV_v1.5.6 from.
The DVD-Recorder does put menus on its products, which is out of my control.
The WMP and VLC media players can open the disc.
I can rip regular (copyrighted, protected) DVD's just fine, without delay.
Note: The DVD's are finalized.

[Debug info]
Using direct disc access mode
Calculated BUP offset does not match one in IFO header.
Calculated BUP offset does not match one in IFO header.

DEBUG: Code 81 at @P}1YXi3R0C.>*9[c:213133457
DEBUG: Code 0 at @P}1YXi3R0C.>*9[c:29393976

Failed to open disc
[End Debug info]

Can anybody tell me what the problem is, and whether it can be solved?

[skittle]

http://www.makemkv.com/faq/item/8/catid/6

[NuVigilance]

http://www.makemkv.com/faq/item/8/catid/6

If what you're suggesting is opening an iso image of the discs, I've just tried it here and I get the same results.

[crowfax]

I think he's suggesting you send the IFO files and debug log as per the instructions on the page.