Apparently, a number of Blackberry issues can be resolved by resending the Service book data. Here is a post (from BlackBerry forums) that tells how to do it:
If you are having problems receiving your email on a timely basis, try these tips below:
1. Options > Advanced > Host Routing Table > Menu > Register.
2. Resend your service books from your carrier BIS site.
From your handheld device: http://www.blackberry.com/btsc/KB15402
From your desktop PC: http://www.blackberry.com/btsc/KB02830
3. With the BlackBerry device powered ON, remove the battery a few seconds and then reinsert the battery to reboot