This morning I opened an open office document by clicking on it in Thunar (xfce's file manager), and the formatting was all goofed up. Weird. I started to mess around with it, but quickly realized the save as menu was different as well, and then noticed I was in Abiword, not Open Office.
For some reason, Xubuntu, which is supposed to be stripped to mostly essentials, ships with Abiword, Gnumeric, and some other useless crap. I hadn't gotten around to uninstalling these, because the clutter they were adding to my Office menu was a minor inconvenience. But now they're gone, kind of.
Removing Gnumeric didn't remove it from the office menu, so I'll have to figure out how to remove it manually, which isn't an obviously simple task in xfce.