Check your composition dispaly settings in the relevant flyout menu and the global preferences (show bounding box and al lthat stuff)
Sorry I dont quite know where those settings options are. Could you please send a screenshot of the location those settings are.
Comp settings: cmd-k (mac) / ctl-k (win).
Preferences: Edit > Preferences.
Removing the bounding box got rid of the lines outside the frame but the random white light are still rendering in the final comp.
Sorry for this issue. Did you ever find a solution? Please let us know if you have or if you still need help.