my network is too slow and also hangs

MY NETWORK IS CONNECTED VIA A PROXY SERVER (MCAFEE ON EPOLICY ORCHESTRATOR SERVER),IT ALSO HAS AN ISA SERVER AS FIREWALL.BUT MOST OFTEN THE EPO SERVER HANGS.WITHEN MY NETWORK (INSIDE) IT IS USUALLY FRUSTRATING TO BROWSE B/COS OF THE SLOWNESS…AND ATIMES ONE CAN’T EVEN BROWSE.PRSENTLY I CAN’T EVEN PING MY MAIN SERVER FROM THE EPO OR VICE VERSA….I NEED HELP.