24" iMac screen issue

[MattSepeta]

So... "Persistence".

I realize that "Image Persistence" can and will happen, especially with how much I use, and how I use my iMac.

I started to notice the photoshop toolbars "burning in" on the side of the screen, as well as some FCP tools burning in as well. Ok, understandable.

-BUT-

Recently, the screen has started to burn in random lines across the screen. They are horizontal lines that seem to be most visible in the neutral tones, like 50% gray and other muted colors.
The lines are most prominent on the left side of the screen, mostly the top. They slowly fade away towards the middle.

I heard that running a colored screen saver or a blank white screen saver for an extended period can help, so I left the machine on over a weekend, at least 56 hours straight, with www.rainbowgradients.com full screen. No dice.

So. Do I just need to let it "wipe clean" longer, or is this a more specific hard/soft ware issue?

{System: Model Name: iMac
Model Identifier: iMac8,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.8 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 6 MB
Memory: 4 GB
Bus Speed: 1.07 GHz
Boot ROM Version: IM81.00C1.B00
SMC Version (system): 1.30f1
Leopard}

Thanks...