[oXygen-user] Can't uninstall/reinstall Eclipse plugin

I need to reinstall Oxygen Author 12, in Eclipse 3.5.2 on Ubuntu 10.4. I have completely cleaned any traces of Oxygen from my Eclipse installation --a file search reveals no files with any form of the string "oxygen" anywhere in the file system. I have restarted Eclipse with the -clean option. No Oxygen-related options or settings are available anywhere in the Eclipse UI. However, when I try to use Help > Install New Software to install Oxygen, Eclipse refuses on the grounds that Oxygen is already installed. What am I doing wrong? -- Ted Kuster help.collab.net