QTR-Quadtone RIP

I have recently developed a printing problem using QTR that I cannot
figure out but it has completely ruined my printing abilities using QTR.

I was doing okay under Win XP, but recently upgraded to Vista and QTR
v2.5, Piezography NK7 and Niagra CIS.  I had a family portrait job I
was finishing up -- e.g., I have printed SOME photos under Vista/2.5,
then I ran a photo through and it showed nozzle clogging or something
of the sort.

I ran the head clean and nozzle pattern SEVERAL times, but did finally
get a good print out.  However, ever since then when I print, it is
VERY  muddy, mid tones are 98% gone only highlights and some horrid
version of darker tones are all you see.  It is as though some nozzle
is leaking at all times, covering up any other printing that is going on.

Here is where it gets particularly confusing -- the calibration
inkseparation.tif prints fine, and print directly from Photoshop CS2
also works (albeit not a great print, it does look 'right').

I have double checked the print files for tif format, greyscale
gamma2.2, uninstalled/reinstalled QTR and the Epson print drivers.

This literally came up in the midst of things working fine -- other
than the fact that I encountered this the first thing in the morning
after having spent the entire day/evening before working on the same
project.

I am really perplexed and I have spent enough time on this to be
convinced that I haven't determined anything except I am 'burning
money' with all the ink and paper I've used.  I've stepped back to
plain desktop printing paper for now, but I am completely 'out of
production' if you will. 

Any help would be GREATLY appreciated.