Your rolodex is already in use!

Either someone else is using and possibly modifying your rolodex, or else
you forgot to exit a previous use of your rolodex, or possibly the system
crashed while you were using your rolodex the last time.

You can find out who is using your rolodex by typing

ls -l ~/.rolodexdata.lock

The third column of the output will be a user's name.  If the name is
not yours, then you should find out what that person is doing with your
rolodex and ask him/her to let you know when they are finished.

If the name is your own, then it is probably safe to remove the lock file.
(It is possible that someone else is logged in as you, however...)
Type

rm ~/.rolodexdata.lock

and then you can use your rolodex.