Well, as a programmer, should not always assume everything in its default settings. I mean, in this particular case, at least let the users get into the installation phase, then only allow the users to alter the settings according to their preferences. But conversely, it assumes everyone had the "program files" directory installed on C. And this is what the programmers failed to anticipate. After I managed to open the setup file, it allows me to change install directory to other location. If you provide this convenience for the users to choose, but why, in the first place, does not allow the users to install? Anyway, the problem is solved by a little trick. I'm sure every program could detect where windows installs its "program files" if the programmers correctly code it to do so. Thanks everybody.