I had this same problem at my workplace. I believe its related to the firewall settings. MS's workaround is located at:
http://www.microsoft.com/windowsmobi...c/default.mspx
Instead of trying to fix it because changing firewall settings would take an act of Congress, I switched to infrared which works fine. Also hear BT works fine. If you research the Axim site you will find others with this issue. I believe this is a WM5/ActiveSync 4.x problem.