Could be many things. Most probable is your gfx card or its drivers issue. It does not have to be. What is your gfx card?
Could be screwed prefs or camera clipping planes set too low as well. If you select View->Select camera in the viewport panel and hit Ctrl+A to get its properties, make sure far clip plane is high enough to display your scene. Crank it up to 20000 or so.
If you bring up the outliner (Window->Outliner) and select an object in this list and then hit F does it zoom into anything? It needs a selection first to frame something, and if you can't see anything in the viewport nothing gets selected right.
Last edited by AlphaFlyte; 12-07-2007 at 01:57 PM.