It still seems like some sort of configuration problem so I think it would be a good idea for you to create a support ticket.
http://support.qbik.com/index.php?_m=tickets&_a=submitIf you can attach the following files so we can take a look at it here.
1. WinGate Registry
GateKeeper --> Options menu --> Advanced --> Save Registry
2. WinGate Config Report
GateKeeper --> Options menu --> Advanced --> Save Config Report
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If the new user "must change password next logon". I try to login this user with a blank pass - it's ok but pass still blank. If I try login with a new pass it access denied(failed). How user have to change it?
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This only works if the users are using GateKeeper itself to log in, it does not work with the java applet etc. I would recommend either allocating passwords or getting the clients to log on using GateKeeper the first time so they can choose a password.