I'm having the same MD5 errors on burned DVDs of Mint 6 XFCE edition (standard Mint 6 edition is fine).
Checksum of the downloaded ISO is OK. The problem seems to be after burning. Tried two times with the exact same problematic results.
Medias were burned on Windows Vista using ImgBurn.
Anyway, I ran the supposedly corrupted XFCE edition in LiveCD mode (without installing in the HD) on a laptop (Sony Vaio VGN-N250E) and everything seemed to be OK. Wireless working, sound ok, touchpad ok, firefox watching youtube videos ok, tested some utilities and everything seemed to be fine. I just couldn't mount the NTFS drive.
Question for the gurus: What is this file "./casper/filesystem.manifest-desktop"? And what problems could it give being with a wrong MD5 checksum?
(The other two files I have an idea of how they work)