It may be broken hardware but try this .... Go to Settings>Applications>Manage Applications and scroll down to and open Gallery (if you still use the stock Gallery app for storing/viewing pix). Clear the cache, force close it, back out to Home screen and restart your camera. I've seen this happen before when something is stuck in the cache. If this works, I'd recommend you get QuickPix from the Play Store. It's free and far superior to the stock Gallery app.