I have the Panasonic ES20 which is probably the quirkiest of the recent Panasonic dvd recorders. In some (rare percentage wise) cases, finalization of a disc freezes right after the progress screen shows up but before the progress bar starts moving. The recorder remains frozen until rebooted. Trying to finalize again ends up the same way. Trying to play the dvd in a Panasonic dvd recorder (S29, from around 2005) says that the dvd is not playable. (Some users of more recent Panasonic dvd recorders said they were able to properly finalize the unfinalizable dvds with the newer recorders).

Yet when I put the dvds in the computer's dvd burner they show up and play automatically - with the generic/bloatware dvd player installed on the computer - as if they were finalized properly - with the typical Panasonic post-finalization screen menus.

(this with DVD-R, I don't use +R often, but if I find any +R with a similar issue I'll try to play them as well)

I've had this same problem quite a bit. It's almost as if there is something on the disc that made the recorder "hic-up" either during recording or while finalizing. I've found that when this happens, if I erase the last thing I recording on the disc, the rest of the disc will finalize fine.