Hi,
I regret to inform you that we do not have Windows 8 support with the current release version as of April 2013. We plan to have full Windows 8 support with Symantec Encryption Desktop 10.3.1.
In the meantime, we can offer to provide best effort support for your issue.
What features are you using Symantec Encryption Desktop for? If you plan to use Email Encryption in Symantec Encryption Desktop I would actually recommend either disabling the digital certificate option in Outlook 2010 and using Symantec Encryption Desktop to import your x509 Digital Certificate as an wrapper key to your PGP desktop encryption key. This will enable you to use Symantec Encryption Desktop for S/MIME encryption and digitally signing of emails. Or you could disable all messaging components as part of the installation of Symantec Encryption Desktop and use the digital certificate option in Outlook.
I think those two options don't usually work together.