I had the same exact problem and it continued for a couple of weeks. I did everything I could think of including removing both batteries and waiting 5-10minutes. I contacted Dell and they sent me out a replacement axim. Although refurbished it looks brand new and I haven't had a single problem with it. It is a much more recent version than my previous one so there are no D-pad issues to deal with. I'm very pleased with their service. I called on a Saturday and it was delivered on Tuesday a.m.
Try removing the batteries and if this continues I would contact Dell. Initially they wanted me to wait 48 hours and they would contact me to see if I still had the problem. I had to convince them this was happening over and over and I didn't really want to lose my data again etc... One good thing to come out of. I'm an expert at backup/restore
Good luck