Photo Editor broken

I am using Microsoft Photo Editor. Recently it has stopped recognizing jpgs.
If I try to open a jpg in it, it says 'Unknown File Format'. I also notice
that in the 'Save As' dialogue box 'jpg' is no longer available as a file
type. It gives the same message for gifs, but bmps are OK. I think it has
happened since I installed Photoshop. Can anyone suggest how I can get Photo
Editor to edit jpg files again? Is it something in the registry? I am using
Vista HP. Thanks