I'm sorry to hear about your issue. The TV takes a few moments to gather information after initial setup; this includes setup after a reset. Additionally, when you initially power on the TV, it'll take up to a minute to gather information for over-the-air channels. So in your two cases, is it immediately after power up you're doing this navigating?
I just purchased the UN55F8000. I do NOT have cable or satellite providers. I get all my channels from DTV broadcast signals (OTA) with an exterior roof-mounted antenna. There are several instances when there is "No Information" shown in the Channel Guide. If I reset the TV, go through setup and go directly to the Guide without changing channels with the remote, the guide will first search all broadcasts for channel information... results: "No Information". If I exit the Guide and change channels using the remote up/down buttons until I see the correct information on the momentary display (on the right side)... then go to the Guide, all channel information appears. The other instance is if I plug in a USB drive (I've tried several), the Guide (which was showing information before) then shows "No Information" for ALL channels. I fix it the same way as mentioned above. This seems to be a F/W issue.