If MS Photo Editor won't open jpg/jpeg files, chances are the graphics jpeg codec found in root drive:\Program Files\Common Files\microsoft shared\GRPHFLT is corrupt. Download a copy (search for JPEGIM32.FLT ) and replace. Has worked every time for me when there's been a problem.
I too incidentally agree that MS Photo Editor is very hard to beat and really don't know why on earth MS discontinued it!
Thanks very much indeed to the member posting a download link for it!