I have the same problem with (Linux centos52-64-fuj 2.6.18-92.el5 #1 SMP Tue Jun 10 18:51:06 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux).
The wireless works perfectly though. One of the old machine with Centos 5.1 with 32-bit is working fine. I mean there is no problem with
Network Monitor. This is strange, can that point to the fact that the 64-bit is not working properly ? Or this problem appears for newer wireless card ?
For reference, my wireless card is
[ckgan@centos52-64-fuj ~]$ dmesg | grep intel
agpgart: Detected an Intel 965GM Chipset.
iwl4965: Intel(R) Wireless WiFi Link 4965AGN driver for Linux, 1.2.22ks
iwl4965: Copyright(c) 2003-2007 Intel Corporation
iwl4965: Detected Intel Wireless WiFi Link 4965AGN
hda_intel: azx_get_response timeout, switching to polling mode...