There appears to be a rather serious problem with the combination of MacOS 10.4.6 and Photoshop (CS) 9.01. Something about this combination is causing printing errors, specifically color relationships are skewed enough to introduce strange spikes in blues or banding in reds and yellows, particularly flesh tones.
I noticed this last week. While printing some photos dominated by flesh tones, I was getting terrible banding. This was particularly confusing, as I had printed these photos before, and I was printing on Velvet Fine art, a paper with a fairly wide gamut. I dismissed the problem as something stupid I had done; printing on Innova FibaPrint paper with Epson's Premium Glossy profile worked around the problem.
But it turns out that this is a real issue; the Adobe forums have a few hundred messages [registration required] on the topic, including confirmation from Adobe people.
"I'm reinstalling 9 on my production machine, and I'd advise anyone printing to an Epson or HP printer to do the same until this gets sorted."
This from Bruce Fraser, who really knows his shit. This problem likely won't be resolved until the next Apple OS update. Given the imminent release of 10.4.7, the fix might have to wait until 10.4.8 (or later). So if you are running MacOS and haven't yet upgraded to Photoshop 9.01, don't.