DM is only added to the Startup Group if during the installation you set the option to include BB Automatic Update to YES. If you set it to NO then it's not added.
Once this pest is in the startup group it's hard to get rid off it, it just reappears. When I realized this I just uninstalled DM and then reinstalled it w/o BB-AU.
BB-AU can also cause problems during upgrading OS from another vendor, discussed here: http://www.blackberryforums.com/gene...-xml-file.html