No, no problem to reinstall.
And, the iMovie 6 HD is part of iLife '06.
iMovie is a custom install from the iLife installer.
Apple did provide a free download of just iMovie HD, when iLife '08 was first released. But, that download disappeared when iLife '09 was released.
Before you do delete the iMovie 6 HD to prepare to reinstall - be sure that you do, in fact, have that iLife '06 or iMovie HD installer. That's your way back.
Again, that "Movie Path not yet defined" should be a button problem (it verifies that all menu buttons are properly linked to valid paths. If not, you get that message). If there's not a good link to the movie from that button, then you can drag your movie file to that button, which will fix that error. More on the link that I posted in post #13, but here it is again :D
http://support.apple.com/kb/PH5422?v...S&locale=en_US