I've deployed a Cisco NAC solution (utilising CCA 3315) in a OOB Virtual Gateway deployment. So far it's working great on XP clients with single sign-on. However when run on Vista clients a problem occurs when the user idles and the screen locks. When the user logs in again, the NAC agent keeps prompting the user to accept a cert repeatedly. Anyone come acrosss this problem and the workaround/solution?