Muddy brown blacks with Epson R280

Hi, sorry to bother you with a question that must be asked a million times a week, but I couldn't find a thread similar to the problem I'm having.  Or I couldn't enter the right words in the search line :).

The problem is that, all of a sudden, I'm getting ruddy brown blacks in b/w prints.  It looks like a driver problem, but I can't talk the tech support at Epson past "please do a nozzle check," or "did you spill coffee on the print."  You know.

In a capsule, I've used this printer in combo with Photoshop CS6 to print many b/w images, and they print well.  Just to be sure it wasn't CS6 I also tried printing the same image with CS5 and a Pentax Silky Pix program.  The result was the same.  I'm using Epson paper and ink, and I have color controls turned off on the printer.  It doesn't matter if the printer is in grayscale or color, or if the color controls in Photoshop are turned off or on.  I still get prints where blacks are muddy brown.

Here's a print example.  Sorry I can't show you the pretty woman's face, as she's the daughter of a friend and is autistic.  Hence I feel funny about showing prints to anyone but her parents.  You can see what I'm talking about -- the two images are using different printer/CS6 setting.  The young lady is wearing a black turtleneck.  The same result shows when I use the Adobe software for printing without Photoshop image controls.

Christiana tests

Can someone point me to tutorials on how to correct this problem?  It appears to me that the deep magenta cartridge is printing along with the black.

Thanks much for you time,

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BAB