I have some problem with CISCO+RADIUS

I have some problem with CISCO+RADIUS user identification. CISCO 3600 is used for dial-up accessing to INTERNET. User’s account is checked with RADIUS Server. There is no problem, when user types his login and password in terminal window (win9x,NT) or uses script, but when term. window or script are not used in general and user types some words (even not correct login&password) only in windows’s “connect to dial-up” password window, identification system does not operate correctly, and user canget access to protected resources. How can I fix this problem.
Beforehand, thanks.