SOS - Please help error code - 25573 and oserr 72

AIX 5.2 IDS 7.31.UD8 Websphere - Max # of users 800 during peak Max # of active sessions during peak : 2800 Nofiles (descriptors) set to unlimited Getting listener-thread err = -25573 oserr =72 errstr= :Network driver cannot accept a connection on the port I am seeing this mostly while user is logging into the system. When it happens sometimes the system hangs or getting slow response. It then clears by itself. This is happenning intermittently, but it is reproducible. Anyone out there has experienced or lived thru this phenomenon. Any help would be greatly appreciated! Thanks!