firmware update
What's new in this version:
When the mode dial was set to an exposure mode (P, S, A, or M) and II selected for the Color mode setting in the Custom item of the Optimize image menu, and then an option other than Custom (such as Portrait) selected from the Optimize image menu, JPEG images captured after this procedure were recognized as having the Adobe RGB color space when opened in applications with a color-management function such as Adobe
Apart from mistaken deletion, many factors, like system crashes...
