The signal bars on the display act differently than the signal bars for the Access.
On a display, the bars are full when a signal is acquired, but then are gradually subtracted if expected data packets have been missed. The Access is a more true signal strength indicator. If there is a least one bar, all your data is being received.
My guess is that there might something electrical near your display that is emitting noise and interfering with the signal. Maybe something light an LED or florescent light. Perhaps a microwave oven. When the device is on, the signal is blocked, when it is turned off, the signal returns.