I've got exactly the same problem, but only since installing SP3.

It happens even in emails that I have created are are in my Sent Items folder.

I don't have any outlprnt.dat file on my machine and the images concerned
are there on the screen but not on the printed paper - all I get is the
"missing image" box with a red X in the top left corner, and they are not on
the internet.

I just tested sending an email to my Gmail address. The images arrived
inline and printed fine, but the original email in my Outlook Sent Items
folder loks OK on thre screen, but they just don't print.

Any help would be appreciated.
Soupie