[CentOS] Lost my menu options again - KDE messes with Gnome?

This was a problem I had a while back. I lost the "Preferences" menu
item in my "Applications" menu in Gnome. After much discussion, the
following commands got my "Preferences" menu item back, along with all
the applications inside of it:

rpm -e redhat-artwork redhat-menus --nodeps --allmatches
yum install redhat-artwork redhat-menus

But...

For some reason it isn't working this time. My "Preferences" option in my application menu is gone, and I don't even know why it left. And doing the commands above aren't getting them back.

Actually, I have some suspicion as to why I've lost my "Preferences" option in my "Applications" menu. Last time this happened, it happened after I installed Amarok and ended up with a bunch of KDE settings I didn't want.

This time, I installed Quanta, which required some KDE libraries, but it didn't seem to cause as much chaos as last time.

However, the implications are that for some reason, having any KDE programs seems to affect my Gnome options.

What's up with that?

Dave