Jpeg links opening in Explorer instead of Picture Manager

[stripedfrog via OfficeKB.com]

I've set up a spreadsheet in Excel 2003 that has links to jpegs. I've gone
back in to add more photos but am having problems with the links. I added 6
photos all from the same folder and all about the same file size. However, 4
of them are giving me the "red x" box.

I don't understand why 2 are opening while the other 4 will not. I've tried
adjusting the file size and moving the files but nothing is working. The
only thing I can think of is that it has something to do with the upgrade to
Explorer 8.

Prior to the upgrade, my photos opened in Picture Manager, now they are
opening in Explorer. I've looked everywhere and can't find a setting to
change it back to the default viewer. I changed the settings under "folder
options" but the links still open Explorer.

Any idea on how to change the setting to open jpeg's in the default viewer?

Thanks in advance.