Wireless radius clients constant reauthentication.

I have a windows 2003 server setup with enterasys and netgear wireless access
points and toshiba and netgear wireless cards in the clients. We are using
WPA encryption with MS-CHAP PEAP.

The setup seemed to go all to plan and the machines authenticate and logon
most of the time. But when logged on they constantly disconnect and reconnect
even when a very strong signal is present.

Is there any reason the radius clients will contantly reauthenticate and can
I stop it? Many files are lost and corruption occurs with the dropouts.
Problems didnt occur when just WEP without radius was used.