Digital BW, The Print

I have a 2200 printer on a Windows XP Home system, and I've just 
installed QTR PC Beta 3 and QTRGui.  I've told QTRGui to print an image, 
and it says that QuadTone RIP is printing, but nothing happens.

The QTRLOG1.txt file contains:
INFO: C:\Program Files\QuadToneRIP\bin\imagetoraster.exe QTRgui_0.28 
amdy FilePrint 1 Pagesize=Custom.11.625x11.625in position=center 
portrait=yes PPD=Quad2200.ppd PRINTER=Quad2200 MediaType=Matte 
Resolution=1440x720hq2 stpImageType=Continuous stpDither=Ordered 
ColorModel=QTRIP ripCurve1=EEM_2200-warm ripCurve2=EEM_2200-warm 
ripBlend=50 D:\Walt\PICT0113-grayscale.tif
PPDFILE = C:\Program Files\QuadToneRIP\ppd\Quad2200.ppd
DEBUG: Page = 837x837; 9,9 to 828,828
DEBUG: Searching for profile "1440x720hq2/Matte"...
INFO: Loading image file...
DEBUG: ImageOpen("D:\Walt\PICT0113-grayscale.tif", 1, 1, 100, 0, 0012F884)
calling ReadTIFF
TIFFReadDirectory: Warning, D:\Walt\PICT0113-grayscale.tif: wrong data 
type 1 for "XMLPacket"; tag ignored.
TIFFReadDirectory: Warning, D:\Walt\PICT0113-grayscale.tif: unknown 
field with tag 34665 (0x8769) encountered.
DEBUG: TIFF resolution = 180.000000x180.000000, units=2
DEBUG: Stored resolution = 180x180 PPI
DEBUG: orientation = top-left
DEBUG: photometric = 1
DEBUG: compression = 1
DEBUG: Creating tile array (8x8)
DEBUG: xpages = 1, ypages = 1
DEBUG: PageSize = [837 837]
DEBUG: cupsWidth = 16380
DEBUG: cupsHeight = 8190
DEBUG: cupsBitsPerColor = 8
DEBUG: cupsBitsPerPixel = 8
DEBUG: cupsBytesPerLine = 16380
DEBUG: cupsColorOrder = 0
DEBUG: cupsColorSpace = 0
DEBUG: img->colorspace = 1
INFO: Formatting page 1...
top:  ht=8190, sz=7680, y=255
ERROR: Unable to write raster data to driver!

Can someone help with interpreting that error message and suggest a fix?

(And yes, I know the PPI is lower than optimal, but I don't think that 
should be the cause of the error.)

	Thanks,
	Walt