I have the same problem and ive tried Revo Uninstaller and it didnt find any trace of evernote on my computer...
When I try to install Evernote 4 on my computer i get 'evernote was already installed by another user. only one user installation is supported. an administrator can intall evernote for everyone after the per-user installation is removed.' I dont understand how I'm getting this when i have never installed Evernote on my computer before..