Sorry you're having trouble with your BB. Here's what I dug up from another forum:
Here's what worked for me: enter blackberry as it requests. when it asks for your password, enter your password as you know it, even if strange type, letters instead of numbers, or numbers instead of letters appear on the screen. do NOT depress the shift, alt or any other key-- only the keys you would press to enter your password. it worked for me.... finally, after 3 full wipes of my device! argh.
Let us know how it goes.