If you see the message "MMC cannot initialize snap-in" and find that MMC has been upgraded to 3.0, downgrade MMC by removing it (if possible) from the main Active Directory Application Mode (ADAM) Server.
System Management Server (SMS)2003 R2 requires MMC 3.0 on administration machines, meaning that additional administrative workstations, where the admin must administer SMS 2003 R2 or other system that requires MMC 3.0, the suggested workaround is to have that admin remotely login to the original ADAM server via terminal services, or VMware ESX, or some other remote administration tool.