Hi,
I tried to duplicate your problem on a Windows 7 box. I downloaded a copy of ELLCC and installed it as close as I could to the way you did. Here are my results:
C:\Users\de023789\Downloads\ellcc-x86_64-w64-mingw32-0.1.28\ellcc-x86_64-w64-min
gw32-0.1.28\ellcc\examples\hello>C:\Users\de023789\Downloads\ellcc-x86_64-w64-mi
ngw32-0.1.28\ellcc-x86_64-w64-mingw32-0.1.28\ellcc\bin\ecc.exe C:\Users\de023789
\Downloads\ellcc-x86_64-w64-mingw32-0.1.28\ellcc-x86_64-w64-mingw32-0.1.28\ellcc
\examples\hello\main.c
C:\Users\de023789\Downloads\ellcc-x86_64-w64-mingw32-0.1.28\ellcc-x86_64-w64-min
gw32-0.1.28\ellcc\examples\hello>a.exe
hello world
C:\Users\de023789\Downloads\ellcc-x86_64-w64-mingw32-0.1.28\ellcc-x86_64-w64-min
gw32-0.1.28\ellcc\examples\hello>
Could this have something to do with anti-virus or something on your system?
‘/’ and ‘\’ are interchangeable in Windows file names when used from programs. Not always on the command line, since ‘/’ is the option character.
-Rich