I use gawk frequently on diffrent systems.
Till now I used version 3.0.3 on Windows 95, 98, Me and 2000. When I tried to use it on Windows XP I saw bug like this when I used pipe instead of input file:

awk: cmd. line:1: (FILENAME=- FNR=1) fatal error: internal error
Abort!

Than I download a new version of gawk (3.1.4) from djgpp. Obviously the above error disapeared, but in this version is other bug:

I tried to use it with pipes and for example I do something like this:

dir /b /s *.html|awk '{print}'>list.txt
dir /b /s *.css|awk '{print}'>>list.txt

Second command override beginning of file list.txt instead appending to the end.
Can You do something with that?