[Mingw-msys] mintty 0.9.7 doesn't work with groff-mingw

I'm using mintty 0.9.7, msys 1.0.17, less 4.4.1 on Win XP.
mintty works fine with groff-1.20.1-2-msys but not with groff-mingw
version 1.20.1

If I do:
groff -Tascii -P-c -mandoc /usr/share/man/man1/bash.1|less

mintty hangs up indefinitely and you cannot proceed any further.
It only works if I do:
cat /usr/share/man/man1/bash.1 | groff -Tascii -P-c -mandoc | less

On the cmd console groff-mingw works fine.

Many thanks in advance,

-- 
Cesar