Blackbaud Intnernet Solutions is capable of creating users on the fly via a web service call. Users encounter Error: Invalid administrator credentials as AdminUsername and AdminPassword POST parameters when adding new users via User Creation Web Service call. Approximately half the time, the web service complains that the Admin user password and/or username are invalid.
Download and install the latest patch which contains all fixes from previous patches. If you are running an older version, download and install the latest version and then the patch.