Applying Web Filter stops all connections to any sites

Hi,

I have a 60E running 5.4.7. I have enabled both certificate and full SSL inspection and both work OK with DNS filter policy. Unit is in proxy mode. When I apply any type of web filter policy all connections to any sites get a tcp reset and browser says 'the site cannot be reached' connection reset. This happens with full or certificate inspection. Licensing and rating connectivity is all working OK. Anyone got any ideas why this would be happening?

thanks