MikroTik

I have very strange problems ...
I have hotspot setup with some profile where i have Idle Timeout set to 20 min.
Problem is that some users are loged out after short time 2-3 minutes ,
and other work fine ... 20 minutes if idle if not idle there is no logout .
Both users are in same profile ... and somebody work , somebody not ,
does anybody have some idea why is that hapens?
Im suspect on win XP SP2 , but im not sure...

SP2 on XP gives me some troubles as well.
Try puters with a decent OS or some routers instead and see if it works...

HM ... These users have Win XP with SP2 , also one have outpost firewall ..
Under win 2000 there is no problems ...
It looks that firewals under XP blocking something ... i dont know what ... and mikrotik "thinks" that host is idle
(also too fast only 2-3 minute - i have setup for 20 minutes?)
... then hotspot logout user.
Does anybody know how mikrotik find that host is idle ?
ping or something other?
This will be usefull to tell users that disable this replay , port or whatewer ...
Also why mikrotik so fast logout user? - this is mikrotik related probably ...