No idea. Are you following this below? Just need to select 5.3 on the install think I forgot to say that. Several of us have done it. Maybe check whether you have any anti-virus blocking what the install program is trying to do.
Download and install the ming-w64-install.exe file from here:
Navigate to: http://mingw-w64.org/doku.php/download
Click the Mingw-builds option then click on the SourceForge link.
Download should begin after 5 seconds.
Run the install file and select "i686" architecture, Posix threads, and Dwarf exceptions.