gfortran 4.8.1 on Windows 7 (undefined reference to 'WinMain@16')

gfortran 4.8.1 on Windows 7 (undefined reference to 'WinMain@16')

I have a Problem compiling some fortran code with gfortran 4.8.1 on
Windows 7. With some fortran programs I get the error message:
c:/gcc/bin/../lib/gcc/i686-pc-mingw32/4.8.1/../../../../i686-pc-mingw32/lib/libmingw32.a(lib32_libmingw32_a-crt0_c.o):crt0_c.c:(.text+0x3c):
undefined reference to 'WinMain@16'
These are not programs that conatain only function or subroutines!
Any help how to solve this problem?
Thanks in advance.
Kind regards
Klaus