Topic: LOGIN FAILED

Hello! I've a problem with my sistem (hotspotlogin.cgi + chillispot + freeradius).
When people try to login with IE or Mozilla Firefox, it goes in login failed and I see the request on my radius monitor as a correct login but a strange caracters password (like }?*[]#@[#@$). But this happens only since 2 years, maybe it depends on new Internet browsers.
But if you save login and password and push rapidly on login 2 or 3 times, you can connect regulary.
How can I solve this problem?