I have a Panelview1000 grayscale that was working fine but recently started flickering once in a while. The screen just flashes brighter than normal then return back to original state. I thought that maybe it was from voltage spikes and have move the power to a filtered power source. This didn't help becuase it still flickers once in a while. Has anyone seen this?

I haven't never seen this. It might be best to send it in for warranty. Knowing AB tech support, they would have asked you do what you did. (install a filter) so I think you've done what you can do to cover your bases. request an RMA.

sounds like problem with background light (probably cold cathode unit...).