Why can I not edit some photos Imported from an iPhone to Windows Vista?
It looks like a complete description of the problem and how to avoid (but not remedy it) is given at Neowin.

Briefly, taking a picture with the new volume button shutter release sets a flag that Windows doesn't understand and so it just gives that vague error message and refuses to mess with the image.

It follows that the images you can manipulate were taken using the on-screen shutter release (?)