I used this one to do the compilation: mingw-mame-w64-QMC2-add-on-20110905. Even by setting options, so it is not finding the folder as the folder ico hash. Is something configured wrong?
1.) Ahh OK, you use René´s package, it´s not my QMC2 add-on.
Check his builds
to find out which files are required to run QMC2.
Then copy the needed files from your Mingw/Qt folder
in your QMC2 folder incl. subfolders.
Do not mix the MingW build files with his official VC++ build files. They are different.
2.) Tools > Options... > Frontend > File/Directories
Set the path for the icon folder, example: data/ico/icons.zip