I had the same problem last fall, but downloading the ROM update seemed to fix it...has only happened once since. Check your current version by going under settings and then system information. If you are not running ROM version A05 (10070400EN), you can download it from here. Just back up all of your information first...it is equivilent to performing a hard reset.

If you already have the ROM update, you may want to try posting the problem in the Axim Site user forums. It's dedicated to Dell PDAs, so they might be able to provide more information. Also, if you're desperate, you can try Dell's official support forums and their live chat with a tech/rep. However, from my experience, the chances of reaching a tech before your hair turns grey is slim to none, and the forums have a lot of questions but few answers.

Hope this helps,
John