I've noticed at times that the first time I have a user visit a portal with a content editor web part on it, they the Office 2003 installer fires off automatically and installs something. This only happens on time per PC... having a little trouble duplicating it. If so, I'm wondering what it is really installing?

I ask because I have a very small number of users among my total audience (18 people out of 9000+ users) who are not able to hit the homepage of my portal (they get the web part maint. page... but no web parts show up with errors). However, they can get in further on the site if they are provided a URL to one of the top level areas. Their browsers do not have the option "install on demand" checked... while others do. Just wondering if this could be the issue. The only web parts on the homepage are three content editor webparts (all of which don't have vanilla HTML... more advanced stuff with JS and such) and one custom one I built. The custom one is used in another part of the portal and the users have no problem viewing it there.