If you're connecting to a Lion Screen Sharing VNC server, you might see a blank screen, a grey screen, or a login screen where you can't click or type:

To fix this, do the following:

1. Upgrade iTeleport to v5.1.1 or higher from the App Store
   
   
2. (Optional) If you use iTeleport Connect, upgrade it to v5.1.0 or higher
   
   
3. Then on your iPhone / iPad, launch iTeleport, then tap on the blue arrow icon next to your computer name, and tap Security.  Set the Authentication Type to Mac, and use your Mac username and password to connect to your computer.