I wish I had time to mess about with tweaking my CAS installation, but having all the attendant hosekeepig that comes with a re-installation of good old XP I gave up after a few days, and uninstalled CAS. Everything works fine now...but being a committed (or committable) Comodo user I might reinstall it if i can discover how to make it let me SEND attachments without it taking and hour per Mb... Crazy stuff.
I'm running the 2.7 Beta on XP with Outlook 2003, and it does not have this problem, if that helps.
Otherwise its difficult for me to help as I have not experienced this problem, sorry
Best wishes
Mouse