On my 7100, I never had problems with the ball disappearing. I actually got up to around 300,000 points and 92 lives and unfortunately had to turn in my BB as I changed jobs. Now I have the Pearl and have had the ball dissapear several time. I noticed this happens when the bricks first start going down, so as someone suggested above, I will wait until the bricks come down two or three times.

Ironically, I have never been able to get my ball back once it goes through the wall. However, it just occurred a few minutes ago and I got frustrated and logged on to the web and found this forum. When I was done reading through the entries I went back to my blackberry, 15 minutes later, the ball reappeared and I lost one life. I am not sure why it reappeared this time.