Where are your images saved, device or memory card?
Overclocked?
Do you have sysklogd installed, if so are there any camera-ui
related logs?
Or run the camera-ui from the command line:
In X-Term as root:
dsmetook -k /usr/bin/camera-ui
(this stops the camera-ui from running in the background)
then as user(!)
/usr/bin/camera-ui
And post any error messages here.

Nicolai