All my installs work fine now, but I remember one install I had to
change the default directory it installed to from Mozilla(?) to
Firefox-3.0.1 or wherever your Firefox is actually installed. Uh,
for Firefox users.

The other time was when I was able to directly install from a page
that asked for it (like the Ultamatix site) and you have to do it
twice, once for the installer and then click on it again, to install
the SWF codecs(?) or something.