Yes indeed your Ethernet11/0 and 11/3 indicate on cabling issues associated with
these ports (assuming your counters were
cleared recently, if not please clear them
again and see if CRCs numbers go up again)
Secondly, do you expierence normal Internet
connectivity from any VLAN/subnet ? or
whole network is affected ?
Did you try to establish connection to the
Internet right from behind the firewall to
exclude all your core devices ?
Did you try Internet access without Proxy ?
HTH,
OW