I guess disconnecting JPEG images from PSP would do the trick, but I don't think that's what Joe's asking exactly.
The problem is multiple PSPs opening up when having multiple images load all into the same PSP would seem more useful.
I can't find any settings in PSPX or X2 that seem to control whether multiple program instances are allowed or not. I don't have PSP8 around anymore to check for certain, sorry Joe.
Y'know, I think I vaguely remember having had the same problem in PSP8 myself, though that was a long time ago now and I'm pretty sure that what probably fixed it was something like this:
(Big caveat here though... I don't have Vista... these instructions should make sense on XP but I'm not sure how close it'll be to what you see on Vista!)
Start as Vidoman suggests by going to Control Panel -> Default Programs -> Associate Filetype or Protocol with a Program
Find JPEG on the list and select that (and you'll probably want to do this again for the other types of image file you commonly use - if it works)
Click the Advanced button. (I'm hoping there's still an Advanced button. There is in WinXP).
You should see a list of actions that includes "Open". Select Open and click the "Edit" button.
The dialog that pops up should show you a field with the full filename for Paint Shop Pro in it. Go to the end of that field where it says "<something>.exe", add a space, then put
Now put a check in the box below that says "Use DDE". This lights up 4 fields to fill in. From top to bottom put this:
Leave the third one blank, then in the fourth one put...
You can click OK for everything then until all the dialogs are gone. Try clicking your two JPEGs, see what happens.
If I understand this right, this way of opening a file is more likely to end up with just one program loaded but with more than one image loaded into it.
Yeeesh, well anyway, thats it - best of luck!
Alli