[My apologies. The links in my previous post were wrong. These work.]

1. Unless you have a specific need for the features found in version 10, you should stick with version 9, which works perfectly well under 10.4. Very few people have any compelling reason to upgrade, other than habit:

ftp://ftp.allume.com/pub/archive/mac/Stuffit_Expander/stuffit_exp_902_x_install.dmg

2. Once again, you can obtain the new version directly, without going to the Allume web site or through any registration process:

ftp://ftp.allume.com/pub/pub/mac/Stuffit/For_MacOS_10.3_and_later/stuffit_exp_1002_install.dmg

3. The cause of the breakage in Norton Antivirus was already discovered and posted in the MacFixit forums:

http://www.macfixitforums.com/php/showflat.php?Cat=&Board=xutilities&Number=752161&page=0&view=collapsed&sb=5&o=31&fpart=1