Try clearing cache in Gallery.
Settings>Apps -or- Application Manager>swipe over to All Apps>scroll down and click on Gallery.
Once there you should see the App Info screen. Click clear cache and then force stop.
i haven't seen this issue before. I would connect your phone to KiesAir and try to download the pictures off the phone on to your computer then factory reset your phone. That should solve the issue. Make sure to back your contacts and any other data you want to save first like emails, texts etc.