Doing some reading on the internet including Googles support site, it shows a lot of people are experiencing issues of some type or another with the app. One suggestion seems to work is an upgrade to OS6 if available for the particular BB model. Be careful if you go this route and only upgrade to OS6 if it is for your BB model. There are other issues with OS 6 that you may want to consider before doing an upgrade. Blackberry Maps is a good app although it does not show traffic. I found it much faster to display and render a new map than Google and TeleNav. I now only use BB maps.
Good Luck