I record to dvd-ram on my pannasonic standalone (E85) down stairs and then use my LG drive to copy the files to the pc, then reformat the disks back down on my standalone

This worked fine untill I changed the LG drive to a new LG super multi drive, files still transfered to pc ok, but when I try to format or record to the disks on the standalone it identifies it as a ram but wont format them or record to them.

I have not to my knowledge altered them in any way on the pc so can not think what could possibly have happend to them.

any ideas?