AD HOC communication

Hello group,

We need to set up a stable ADHOC network between a pda and a WINDOWS XP
Professional machine.
Everything goes fine until the PDA goes to far away from the XP machine.
When the PDA comes back the WIFI connection has been lost and it doesn't
come back anymore.

Is this a know issue? Is there an other solution than placing a wireless
bridge (wifi router) between the XP machine and the PDA?
Maybe a patch, maybe some configuration settings?

Best regards,
Mobile boy