MacBook Pro :: Epson 9800 Laying Down WAY Too Much Ink?

I use a MacBook Pro to print to an Epson 9800 roll printer -- been doing this for years with no problem. 

UNTIL NOW! All of a sudden, the Epson is laying down huge quantities of ink, especially when I print onto film (for screen printing). It puts down so much ink, the ink dribbles down the film and drips off the printer, pooling on the floor, until I leap up and cancel the job. What's more, the printer is printing a light-colored background to images that had no background to begin with. 

Here's the catch: *this only happens in Photoshop.* (I'm using CS 5.1.) If I take the same image file, place it in Illustrator, and print it, it comes out just fine. So the problem lies in Photoshop's print options. Somehow, something got changed in the last couple weeks, and I have no idea what. 

I'm hoping that someone here will be familiar with this *particular* printing problem, and what the *specific* Photoshop printing option might be that is causing this.

Info:
MacBook 2.4 GHz Intel Core 2 Duo, Mac OS X (10.5.6)