W2K Update Site

Is anyone else having a problem with the W2K update site when behind a Netgear RT311 gateway router. I can access the site and the catalog loads normally. I can select the desired updates and thelicense agreements function. The proccess fails on either the download, or if that completes then the installation fails. Computers in question update OK when not behind the router. Problem started about 2 weeks ago and rebooting the routers has not cleared the problem. Any ideas?