Try removing the channels from the Roku home screen by navigating to the channel tile, pressing the * key on your remote and choosing 'Remove channel'. Then restart your device from Settings>System>System restart. Once your player starts up again, add the channels back once more.
Does this clear up the issue you are seeing? Please keep us posted what you find out.
Can you please provide us the following information:
-Roku device model
(these can all be found in Settings > System > About)
-does this issue occur on a specific channel? if so, what channel and what version/build is the channel (this can be found be selecting the channel on the Home screen and pressing the * button)
-tracker ID when this issue occurs (when you see this issue occur, press the Home button 5 times, followed by the Back button 5 times)
-steps to reproduce the issue you are seeing
Once we have this information we will be able to look further into the issue.