U4R date keeps changing

[michaelwerk]

When I set the date in the menu it only lasts a little while, maybe a few days, then it resets, usually to a 2004 date. I do not use the date to print onto the pictures but I do use the exif data to organize my pictures in Apeture.

Is there a way to stop it changing and is there a way to change the exif data after the fact?

Any help much appreciated