Help! Threads not displaying in order

[mp3u]

All of a sudden threads in all forums are displaying in almost random order across all forums on my site. I can get this fixed by clicking 'Last Post' on the nav bar for each forum I am in but my users are starting to complain that their posts are missing. How can I set the default for all users to be that the last posted thread appears first and continues chronlogicialy down the page?
Thanks for any help on this in advance.
D

[snakes1100]

UPDATE user SET options=options + 32768 WHERE NOT(options & 32768)

[mp3u]

Sorry, I'm a complete novice when it comes to code... what do I do with that (sorry for noob question)?

[snakes1100]

Run it in phpmyadmin or in your admincp under the maintenance section "execute sql query"

Backup your DB before doing anything.