Can't save edited Photo Gallery pics

Dear all,

In some subfolders in the My Pictures folder, Windows Photo Gallery won't
allow me to save edited pics. Whenever I try to save any changes, even simply
turning the picture around, and message says, "An error is preventing Photo
Gallery from saving this picture." before closing.

I also have a problem with the Windows Sidebar - it won't allow me to open
any pictures that are running on the Slideshow. An error appears saying
"interface not supported".

What the hell's going on?? Any suggestions are much appreciated.

Adam