There is a KB article that refers to this problem and
appears to have fixed my own situation. You can search
for the article yourself to confirm instructions, but I've
pasted below for ease:
WARNING: If you use Registry Editor incorrectly, you may
cause serious problems that may require you to reinstall
your operating system. Microsoft cannot guarantee that you
can solve problems that result from using Registry Editor
incorrectly. Use Registry Editor at your own risk.
To resolve this issue, use Regedit to associate the .jpg
file extension in the registry:
Click Start, click Run, type regedit in the Open box, and
then click OK.
Locate and click the HKEY_CLASSES_ROOT\.jpg registry key.
Right-click the HKEY_CLASSES_ROOT\.jpg registry key, point
to New, and then click Key. Name the new key ShellEx.
Right-click the ShellEx registry key that you created,
point to New, and then click Key. Name the new key
{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}.
Click the {BB2E617C-0920-11d1-9A0B-00C04FC2D6C1} registry
key that you created, right-click the Default value in the
right pane, click Modify, and then type the following
value data in the Value data box:
{7376D660-C583-11d0-A3A5-00C04FD706EC}
Good luck!