That is the same error I am getting for the 1394 port on my Audigy sound card. After I pulled the card out and rebooted XP is failing to rocognize the card correctly and refuses to recognize the 1394 port at all. Even after I installed the original drivers.
I think XP may have a bug in recognizing hardware after you pull it. I read an article to this effect someplace but I can not remember where right this minute.
My computer may be down for the count. I am running the internet off my wifes computer temporarily until I get mine back up. I do not have all my bookmarks is why I can not locate the article right now.
AGP does have an IRQ assigned (10). The bios does support fast write. I have tried the same setup but on a different motherboard (same hd, gpu, sound and os) and am still having the same problem! So, this is definately win xp going bonkers in some way. If any1 requires any more information to help diagnose the problem I would be happy to give it, i can't do much else with 4 bit colours can i?
I got that same error with my WinXP Pro when I tried to install a second graphics card (one AGP and one PCI) for dual monitors. I could not figure it out, had to do a clean install of Windows XP and haven't had a problem since. Good luck.