MMC errors on closing

I installed service pack 6a. Then I installed MMC 1.2 off the Symnatec Cd’s for the Enterprise Firewall 7.0. It replaced the earlier version, 1.1. Everthing works. But when I close the program, I get a MMC.EXE – Application Error, The Instructions at ” ” referenced memory at ” ” The memory cannot be read. Any ideas?