I've had the same problem with the black rectangles appearing on landscape oriented pages where a smaller image was placed onto an 8x11' page. I had used the Photoshop HP plugin as well, and had selected that the printer to not do any scaling.
One print had 2 rectangles at the right edge, top and bottom. After moving the image up a bit, I only got a black rectangle at the bottom.If anyone wants to see how this looks, let me know and I'll attach or url a jpeg.
My workaround last night was just to crop the image and get rid of the faux matt area and click the Pshp printer setting to center the image on the page. This looks like a workaround, but I'd rather the HP people fixed the plug-in so none's needed.
I've had the printer about a month, and had brought a print with the rectangles to the HP booth at the recent MacWorld (though I'm using a PC, btw). At that point I'd only had the printer a few days, and I'd only had that problem once. However, the rep advised I should contact HP if the problem recurs.
I'm hoping others will let them know. Don't know if the HP people read this forum. But it does sound like something's off with the Photoshop plug-in. The reps at MacWorld really felt I should stick to their PShp plug-in to get the most consistent results of matching up what one sees on screen with the print.
My biggest concern was their lack of support for any papers other than theirs. I think this is not only unrealistic but shooting yourself in the foot when the Epson people seem to be bending over backwards to be compatible with other papers. Epson's dominated this market, so HP should be competing by being as compatible as well as giving us a better printer altogether without the grief of the Epson clogging printheads. However, I digress here.
Wondering Dark Penguin if you've had any recurrence of the black rectangles, or if you've cirumvented this problem in some other way?
Got my new printer. Replacement ink and paper included. Had to use the old print heads.
This one has the same issue as the old one. I have an image sized to the sheet of paper it is going to print on. 8.5x11 in this case. The image has a fake white matte. When I print this borderless at 100% I get one or more odd black rectangles printed in the white "matte" area of the print.
This isn't a real interesting problem since I've only about 2 images done this way and it doesn't seem to happen on normal borderless images (those that the actual photo is edge to edge) or on images that are printed smaller than the given media size. (Which would be about 99% of what I print.)
Anywho. The new printer works fine except for this one odd issue.
I'm still shocked they sent me a new one. It had a "I don't know, try a new printer." feel to it. I doubt I'm even going to pursue this any further. I just want them to enter it as a defect and try to fix it if they ever see the issue.