This problem appears to apply to multiple XP clients connected to a 3Com Baseline2948 Gigabit switch. The clients don't share a common network card, some are Intel based, others nVidia. All clients are, however, connecting at 1000Mbps/Full Duplex. This problem doesn't apply to all clients, only a handful.
What's happening is that software installation via Group Policy won't fire, and I get Event ID 1054 "Windows cannot obtain the domain controller name for your computer network...Group Policy processing aborted". There are often other errors related to group policies, DHCP, DNS, and so on...but this varies from client to client.
The fix, I've found, is to disable DHCP media sense for TCP/IP as outlined in this MS kb article.
As soon as I do that and restart, all of my group policy troubles completely disappear and everything functions normally.
So my question is, why would this be happening... and is there a more appropriate fix?