I'm sorry to hear that you're having troubles.
I haven't heard of this symptom before. You might try unplugging all of the HDMI connections, and holding down the EXIT button to see if you can get the system to restart. If not, attempt to run the Plug and Play option in the TV to see if that fixes the issue.
If none of those satisfy the issue, I'd recommend calling the Samsung customer service center in your region.
We got a LA46B650T1F 46' LCD Samsung, Problem is: whatever is plugged into HDMI 2 outputs to all the other HDMI channels even when they have things plugged into them. DOes anyone have an idea. Have had this happen before tech came out and fixed it, he replaced the Mainboard 4 months ago and it worked fine up until now and it has happened again. Has anyone come across this and if so how did you fix it.
Thanking you very much in advance.