It seems that the Windows Installer is reported as infected by some antivirus software. This is a false report and you can safely run the program on your system: if it happens, please contact the antivirus' vendor so they can fix the issue as soon as possible.
Due to some ACL issues with Windows Vista and Win7, haXe will install itself in C:/Motion-Twin/haxe on these systems. Sorry for the inconvenience but using ProgramFiles was causing too many issues.
Это вы ещё их linux installer не видели.
world-writeable /Motion-Twin/haxe он, скорее всего, не создает, но тарболл в 2010 году - это кощунство.