Eventually, someone will pass this way and either ask the following or tell you to do a search, so I'll go ahead and do the nice thing and suggest some things to do.
The question will be: are you on BES or BIS?
If you're on either BIS or BES, pull the battery for a few seconds and see if that doesn't clear it up. Failing that, if you're on BIS, log into your service providers BIS website and resend the service books to your handheld. You may want to follow that with another restart and/or going to Options and look for Host Routing Tables. Open that and click the list anywhere and select "Register Now."
If none of this works, I'd call Alltel back and ask them exactly what you're paying them for if they can't help you
This should give you something to do until someone with actual technical knowledge sees your post.