Limewire Pro (A question and or problem)

Whenever I try to install it, it won't let me install it on my Macintosh HD. Is there some requirement amount of space I need? Also, it HOWEVER, lets me install it on my external drive. BUT, I don't want to install it on there, as I fear it could ruin it.

So, my question(s) are:

1. What do I need to do, to install it on my Mainctosh HD?

2. If I can't install it on there, and if I install it on my external drive, will my external drive be ruined by the installation?

Thanks to anyone who can help! (Move the topic to the appropriate place if in the wrong forum).

have you installed it before?

You mean a version of it before this one? Or just basic free Limewire? If you mean a version before it then, no. if you mean the basic free Limewire, yeah I have that installed.