If you are willing to open up your Axim I can show you what you need to kill/remove/relink in order to get rid of the warning. From what I've heard there is no way to disable it in software.
In this image (courtesy of
Afarre) the switch you are looking for is directly up from the supercap (battery like thing) and almost in line with the centre of the sync connector.
http://allyoucanupload.webshots.com/...33614687064064
If I was having that problem I would open the Axim up, take a multimeter and work out which contacts are made when the latch pushes against the switch. I would then snip off the switch and solder a piece of wire across the contacts that tell it the latch is closed... It means it will *never* detect it open again, but hey, I'll know it was open because I opened it dang it! :D