I built gcc 4.1.2 again on Cygwin but this time with pthreads. No problems at all during compilation.
Output of config.guess: i686-pc-cygwin Output of gcc -v: Using built-in specs. Target: i686-pc-cygwin Configured with: /home/jesper/gcc-4.1.2/configure --enable-threads=posix --with-cpu=i686 --with-arch=i686 --with-tune=i686 --enable-languages=c,c++ Thread model: posix gcc version 4.1.2 Languages: C, C++ Jesper de Jong The Netherlands