If ActiveCGM has previously been loaded on this PC, you may need to uninstall it before doing the reload.
Go to a Command (DOS) prompt.
Go to the main windows drive. Type "c:" if you are not already at the "c" prompt.
Change directories to the Windows directory. It probably is "cd winnt". For Windows 95/98 it may be "cd windows/system"
Type "regsvr32 /u acgm.dll"
Wait a couple of seconds and you should get a message that the control was unregistered.