r.out.tiff error

I got the following error when I ran r.out.tiff:

Mapset <sue> in Location <sfbay>
GRASS 4.1 > r.out.tiff input=counties.12 output=c12.tiff
TIFFAppendToStrip: c12.tiff: Write error at scanline 1901.
c12.tiff: Error writing TIFF header.

Any suggestions?

Sue Huse
REGIS
UC Berkeley