Id like to thank you for using our answers forum and am glad I can be of some help. I see you are having problems after getting IOS 6.0 on your Iphone 4. What I would suggest is trying what is in this video ill post below:
I would suggest using the component hook up over the HDMI and see if this cures the issue. I believe the HDMI should work if everything is up to date as ling as the cable is from Apple.
Hope this helps,
Sling Moderation Team