Most always, the fault lies first with antivirus software, and secondarily with port monitoring software.
Norton AntiVirus Corporate Edition software, versions 7.00, 7.01, 7.02, or 7.03 are known to cause this (but not necessarily limited to these products): http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q272568&
A hunt on Google returns the same information, and also suggests that
attacks on net meeting ports can cause this. As a personal observation, I never had this problem (and I have been running WebX in Win2K for 3 years contiuously) until one time I accidently left my firewall wide open for testing and forgot to tighten it back up. One morning I woke up to this same situation. No doubt an attack of some sort on an open port caused this.
Also see http://www.secureroot.com/security/advisories/9876756313.html (WCI is not affiliated with this site nor takes any responsibility for data, claims, recommendations, etc they may make).
Other customers have had something similar occur due to odd interactions
with their firewall/port mapping and NAT configuration.
Others have suggested this problem could be due to power saving options within the OS.
And as per Microsoft: "This behavior can occur because the kernel-mode tag, Dynamic Access Protocol version 4 (DAP4), is leaking memory. This tag is provided by 3com. The tag is a driver that is loaded into the computer for the 3Com 3C980C-TXM network adapter.". See Q294346