Usually the blank page with grid lines from Maps 3D appears when your iDevice tries to connect to internet to download that respective map. Just a hint: maybe your internet connection has a bad signal.
If you have a lot of apps and you are using an iPhone 4 device, then try not to activate your 3D option from maps. I did activated it and my iPhone 4 went crazy. It's performance decreased visible, and after one day it messed up my whole Maps app. That's not for us. maybe it will be, but not now, not soon!