I hope someone can help me figure out a problem with scanning dark photos!

I've owned an HP Scanjet 6100 for about 2 weeks; before that I'd used Scanjet 4C's at Kinkos, as well as a high-end UMAX at work. Anyway, in all these scanners I've noticed a similar problem when scanning color photos with dark backgrounds. There seems to be a whitish "banding" (NOT "parallel," but close) within the top 1.5" of the scanned area.

When I first used my new Scanjet 6100 I was relieved to see that that "defect" wasn't present. Now, it's begun to appear.

Having noticed this issue on other scanners, here is/are my question(s): Is this "normal"? Is the banding a sign of defective product on HP's part, or a sign of user maintenance on my part? Is there something *I* can do (e.g., turning off the scanner when not in use) to reduce or eliminate these occurrences?

Thanks for any help, advice, or recommendations you can provide!

-- Conrado Bondoc (BreezeBos@aol.com), May 17, 1998