Since I have updated my Cygwin to the latest version calling postmaster 
core dumps. This is probably not an installation problem because 
everything was fine before. Also this happens independently on two 
different machines. Also removing the default database and creating a 
fresh one with initdb did not help (while initdb worked fine!).

I have attached the output of cygcheck -s -c and postgres.exe.stackdump. 
Here is the relevant part of the output.

> $ /usr/sbin/cygserver.exe -v
> cygserver: (cygwin) 1.12
> API version 1.5.18(0.132/4/1)-(3.0.0.2) 2005-07-02 20:30
>
> $ postmaster -V
> postmaster (PostgreSQL) 7.4.5
>
> $ postmaster -d 5 -i
> DEBUG:  -----------------------------------------
> DEBUG:  searching PATH for executable
> DEBUG:  [...]
> DEBUG:  found "/usr/bin/postgres" using PATH
> DEBUG:  invoking IpcMemoryCreate(size=10461184)
> Segmentation fault (core dumped)

Has anybody an idea?

Frank-Michael