The messages on a Blackberry started to appear in reverse order. The oldest messages are on top and the user has to always scroll or skip through the messages to see any new messages.
I don't see any option to change the display order in the 7290 simulator or pdf manual.
What causes this and how is it changed so the newest e-mails appear on top again?

Not sure what could changed the order of the messages. I will suggest removing and reinserting the battery to hard reset the BlackBerry. Let us know if that helps. If not, someone else might have another suggestion.