It turns out I was mistaken when I said that I’d fixed the problem with the WMP54GX and Service Pack 2. Every 30 minutes the PC would reset itself. Fortunately I had a Norton Ghost backup that I used to restore my PC to normal - back to good old Service Pack 1 again. I’m definitely going to start looking for an alternative 802.11N wireless card.
I hope owners of the Linksys WMP54GX card find this post helpful. Linksys build pretty good hardware, but their software and support are absolutely dire. There hasn’t been a driver update for the WMP54GX since 2005, which is pretty slack. Users have also reported compatibility problems with Service Pack 2. My solution to this issue was to only use the Linksys drivers, and not the dodgy software. The solution seems to work thus far.
Hope this helps others too.
