strange lag

i have a very strange lag.
when i join other ppl maps and porting in i get 0ms and game freeze(not fps freeze, lag freeze).
i relog and in town the ms is normal(90-110).
when i try to leave town i get lag freeze.
somtimes i need to relog 5-6 times before the game lets me play with normal ms.
it never happend to me before, my ms is perfectly normal, i never had lags...
btw this happens only when i try to group up with other players.