Every time I've seen your particular "Unknown" it's meant that the app/utility that placed the login item was not in its original location...either gone from my deuced Mac(hina) or moved.
If those items still appear in /Applications/System Preferences > Accounts > Login Items you can just delete them. (I don't recall a login item ever just disappearing when its source disappeared.)
The new Great Equalizer is the SEND button.
In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire
