I had to install IE4 on my machine that already had Netscape....and here is what happended.

1. IE4 made itself the default browser without my approval.
2. Some plugins in Netscape stoped working. I had to uninstall netscape....reinstall it and then reinstall the plugins to get it to work properly.

Since I've only done this a few days ago...I dont know if IE4 contains any other "un-documented features"