L2TP VPN Bug with 3 Concurent Session

There is a bug in the Windows IPSEC driver that only allows 3 simultaneous L2TP connections to an ISA server from a single location.  The IPSEC session may linger after a user disconnects so it’s not always apparent by looking at the number of connected VPN users.  Installing the following hotfix corrected my issue: http://support.microsoft.com/kb/912213