Did you try to burn it as slow as possible? That is what everyone recommends.
I check the md5sum before I burn anything. Saves on disks too!
If you haven't completely given up, try this site. http://ftp.heanet.ie/mirrors/linuxmint. ... Mint-7.iso
Very fast for me in Canada, and the md5 has always been correct. (hope I didn't just jinx myself