Pocket PC and AP problem

I have a Toshiba e750 with integrated wifi card and an Avaya access
point AP-2000. My problem is that when after I use a wireless
connection my AP fails after about 30 minutes.
The only solution I find is to reboot my AP.

It's a problem with my Toshiba PocketPC because all work fine with my
PCs (Avaya Gold card) and my Toshiba TabletPC.

Has anyone the same problem ?
Any ideas would be greatly appreciated.