Wireless Users Chat → isp login portal issue

PLEASE IDENTIFY THE PROBLEM.
I AM WORKING FOR ISP ,WHEN USERNAME AND PASSWORD ENTERED IN LOGIN PORTAL EITHER WE GET AUTHENTICATION IS IN PROGRESS OR NULL ERROR ,EVEN IT SHOWS ERROR IN PORTAL SESSION STARTS AND BROWSING CAN BE DONE BUT THE PROBLEM IS UNABLE TO GET LOGOUT PAGE ,IF WE LOAD LOGIN PORTAL AFTER LOGIN STILL ASKING FOR USERNAME AND PASSWORD BUT NOT LOGOUT PAGE , WHAT WOULD BE THE POSSIBLE CAUSE .
WHEN DIAGNOSED IN WINDOWS SHOWING DNS RESOURCE PROBLEM.
WE HAVE DONE ALL TROUBLE SHOOTING AT CLIENT END LIKE MANUAL DNS IP , FLUSHING DNS , REINSTALL DRIVERS AND BROWSER ,BUT WITH SAME USER ID IN OTHER LOCATION WORKING FINE FOR SOME TIME .
NSLOOKUP FOR BOTH ISSUE AND NON ISSUE LOCATION ARE SAME

IS IT ACCESS POINT ISSUE
IS IT SESSION MANAGEMENT ISSUE
IS IT LOGIN PAGE APPLICATION ERROR
CAN ANY ONE IDENTIFY THE PROBLEM WHERE IS THE ISSUE

OK I IDENTIFIED THE PROBLEM FOR YOU.

THE MARTIANS ARE NOT ALLOWING IT TO WORK PROPERLY AND IT DOESN'T MATTER WHAT YOU DO.

TRY TALKING TO THEM nicely instead of SCREAMING AT THEM

sheesh