Permissions Problem - Photo Editor

We have recently upgraded all our machines to Windows XP
in our organisation. Since the upgrade, all users are
unable to open jpg's directly from Outlook. Their default
graphics program is Microsoft Photo Editor. When they open
the attachment, Photo Editor opens, but they get an error
message that prevents them from opening the file. When we
give the user 'Power User' permissions on their local
machine, this solves the problem and they are able to open
their jpg attachment through Photo Editor without any
error messages or problems. We are running Server 2000
SBE. All clients are running WinXP SP1a, Office 2000 SP3.
This is purely a WinXP permissions issue. Ultimately, we
do not want to give everyone 'Power User' access rights.
We want to keep them as 'Users'.
Thanks for your time and replies.