This past Sunday right at 4:15 a.m. when I was surfing I witnessed my screen on my iMac make a sound and then went dim. I mean dim. It also went into a negative state. It's a 2.16 Ghz Intel Core 2 Duo with 3 gigs of ram. I've been through all the setting for brightness and changed it around from positive to negative in Universal access but it's still very very very dim. It works perfectly with everything else. It's just super dim. So I have an extra monitor and hooked it up to the output on the back of the iMac and I am mirroring the screen. The external looks normal. In Universal Access, when I choose Black on White...the iMac is in a negative state and my external monitor is positive and it looks fine. When I switch to white on black my external goes negative and my iMac goes positive but is still very very dim. I've called Apple and since the warranty is up on it...nobody wants to give me a low and high ball park figure over the phone of what I might be looking at in cost for repairs or what the issue may be with this. Any help would be appreciated.