WPA-PSK problem. Client getting DEauthed - RC 4.

We have a bunch of WiFi enabled PDA clients that seem to have an issue
with WPA-PSK. They seems to work fine for about 1 - 2 hours, but then
they are knocked off the network. Running a wireshark trace it showed
that the AP sends 3 WPA-PSK handshakes that the PDA never responds to.
The AP then sends a DEauth with reason code 4 - which indicates that
the AP or backend controller cancelled the session due to inactivity.

Access point: Cisco AIR-LAP1242AG-A-K9.

Anyone experience this issue? Anything to look for?

TheDood wrote:
> We have a bunch of WiFi enabled PDA clients that seem to have an issue
> with WPA-PSK. They seems to work fine for about 1 - 2 hours, but then
> they are knocked off the network. Running a wireshark trace it showed
> that the AP sends 3 WPA-PSK handshakes that the PDA never responds to.
> The AP then sends a DEauth with reason code 4 - which indicates that
> the AP or backend controller cancelled the session due to inactivity.
>
> Access point: Cisco AIR-LAP1242AG-A-K9.
>
> Anyone experience this issue? Anything to look for?

What types of PDA, and is it native support for WPA or an addon program?