Black screen/blank photos after taking a picture.

Hi all. I've had a HS50exr for a while, and I've found a new issue. When I turn the camera on, even in well lit rooms, the screen and the photos seem very very dark, even with suitable settings for the light. But the main problem is, after taking a photograph, when the preview disappears, I return to the normal screen, but it is completely black. I have to adjust the zoom for any kind of picture to appear. It's as if the camera does not sense any light entering the lens until I adjust the zoom. I cant think of a good reason as to why this might happen? any advice? thanks in advance