Slow 802.1X Authentication

[Michael Chau]

Why my 802.1X authentication is so slow??

PEAP, MS-CHAP-V2

Domain user login and password. Zyxel 802.1X Radius Client Zyxel GS-2024
IAS using Windows Server 2000 AD using Windows Server 2003 Standard
Windows XP service pack 2.

It takes more than 1mins from type in the logon domain password to seeing
the desktop icons. And mapping folder using logon script sometimes failed.

Any solution ??