Unfortunately sometimes Twitter's API returns temporary errors.
These errors are fixed by Twitter within a few days, but they often result in your account loading incompletely for a limited period of time.
Specifically a block around 100 of your followers or friends may not be able to be loaded. Every part of ManageFlitter will continue to work correctly, however until Twitter resolves the error, you lists will exclude these people. No action is required on your part to resolve the error.
Please contact us if you have any further questions.