Start > Settings > Control Panel > Folder Options > File Types
..bmp
..gif
..jpg
..tiff
(and others)
It is possible one of these "Extensions" to "File Types" associations has
been changed (by the kids). This controls what program is used by "default"
to handle a file of that type. So when someone sends you "test.gif" (or
"party.bmp") the computer "knows" what program to open it with. By default
"Internet Explorer" may be the program for SOME image types, but you have to
look over the list. Use the "Change..." button in here to browse a list of
"Programs" available on your system.
Many image handling programs modify this "filetype association" when they
are installed, so if your kids downloaded something and allowed THAT PROGRAM
to take over the handling of one (or more) file types, this could be the
problem.
"Why does nothing happen now?"
Because after downloading, installing and modifying the image handling
settings, the kids realized they shouldn't have done that and uninstalled
the downloaded program. Now Windows does not have "any program" specified
for showing you the images so clicking on them does "nothing". That
situation USUALLY does not happen, so there could be another cause as well.
I hope it helps!
DISCLAIMER: My opinions and comments are mine alone and do not represent
any other person or organization, living or dead. This includes any
government organization, DoD contractor, local brew pub or convenient store.