Sharp YO-390 Organizer problem

This is the closest newsgroup to this topic... sorry for not being exactly a
palmtop question...

Been using this old thing for many years. Nice little organizer, but today I
entered an address, turned it off as usual, then an hour later turned it on and
get this error message on the screen....

"Data has been impaired! Press Y to clear all memory."

I have a recent backup but still will lose some addresses.
Anyone run across this before and any suggestions on the last ditch effort to
salvage the data?

Thanks in advance.

Fred