hi bonzo

My wife had a similar problem with her Panasonic camera.

Luckily she had lost only a couple of pictures. At the time we were near an photographic shop and they told us that we should always only format an SD Card ( or other USB media) on the camera.
Since then we have only deleted pictures on the camera itself and only formatted cards there. We have had no problems since.

I have had other cameras Canon, Nikon etc where I always deleted and formatted cards on the computer - XP at that time- without any problems.

But now we always copy our pics to a backup file so that if we have any such problems we still have the pictures.

Cheers

Mike