SOLUTION:
Students should now use a 9-digit format of their SID as a login username.  Simply add a zero to the end of your old eight-digit SID; for example, a student who had been using '20049999' should now use '200499990'.

 If you are using a saved username/password to log in, be sure to clear out the previously saved username/password pair from your web browser.

Prior to 2007, students were issued an eight-digit Downstate student ID number (SID).  That SID is used as a username for logging into a variety of systems - email, Prime and Prime-Portal.  In 2007, the switch to the Banner student database necessitated the use of a nine-digit SID.  On Wednesday, January 9, 2008, various systems were updated to use a 9-digit format for the Downstate student ID number. 

The old eight-digit format was not removed from the campus authentication server, but will no longer work with Prime.  If you use the old eight-digit format for logging in, you will receive an error message

"The username you've entered is valid, but does not have permissions to use this site."

JMN - 14 Jan 2008