Let me correct my earlier post on this thread. (I posted as "Gantthead" on 22 Jun 03. I forgot my handle and had to re-register.)
The four steps I specified did NOT solve my problem in the end. It worked only until the next warm reboot, after which the problem resurfaced. After much discussion with Linksys, I eventually returned the Linksys PCI card to the store and took a Microsoft USB WiFi adapter in exchange.
I would have preferred a D-Link PCI WiFi card or something similar, but the store only carried Linksys PCI WiFi cards, Linksys USB adapters and Microsoft USB adapters. BTW, the Linksys USB adapter had the exact same problem on my PC as the Linksys PCI card had.
The Microsoft USB WiFi adapter is not my first choice, but at least it is an effective resolution to the stubborn Linksys PCI problem on my XP box.