Yes, have backups from the original card saves on drive that is usually turned off and generally not used, no edits/xmp. So far there have been no problems there.
I usually work with the CR2 files until all my edits are done. Convert to DNG would be my last step, but I don't always get to it.
Any thoughts if DNG files would be less likely to get compromised?
I have not tried deleting the xmp to see if I can open the file, reimport, or open in camera raw.
What bothers me is that I haven't had this happen before. Occasionally, I have old had files on a CD that would not open, but not from a hard drive. Guess I've been lucky. Will have to put more stock in backups.