I had this same issue on my Bionic. I use google voice but somehow before I got it going a voicemail snuck in.
To get rid of it and are on google voice you will need to log off, dial *73, *900, *920
Then call your phone and leave a voicemail.
Go to the Verizon voicemail app and call in, delete each message when the option is given. Once you delete the mystery messages you will need to reconnect to google voice.
I used the guide at the following URL to get google voice working on the Bionic
How to set up Google Voice voicemail on the Motorola DROID BIONIC - Know Your Cell
Hope this helps.
Lorraine