Can't copy from Outlook 2007 and paste in Publisher 2007

I'm using Outlook 2007, and it appears the copy/paste function is broken.

When I copy text or images from some emails, I can't paste them into
Publisher 2007 or Photoshop Elements 4. When I paste text into Publisher
2007, the text I just copied from Outlook doesn't appear. Instead, text I had
previously copied is pasted. When I try to paste an image into Photoshop, the
"File/New/Image from clipboard" menu item is grayed (not available).

This doesn't happen when I paste into other programs. For example, when I
paste into Wordpad the correct text or image is pasted.

What is broken in Outlook 2007? How can I fix this?