This comes with a bit of a story just because of how weird the problem is.
I have a Dell Inspiron 9400 with a Dell 1390 wireless card (based on broadcom chipset). I've never had an issue with the card, worked in Gutsy and Hardy with absolutely no issues.
Last week I decide to format my Ubuntu partition. Wireless stops working, card is detected but can't see any networks...I assume it's Ubuntu so I reinstall again with no luck. I decide to go into my XP boot, same problem, card is seen but no networks are visible. At this point I am getting pretty irritated, as I foresee one of two issues, wireless card went out, or antenna went out and I am out of warranty. To test the issue I put my girlfriends Atheros card in my computer, it works, I'm happy, antenna would have been much more difficult to fix.
Next step, I order a Dell 1490 for my computer (refurbished for $30 :) ) I get it yesterday, pop it in my system, no luck, same issue, card seen in both Ubuntu Hardy and XP but no signal from any network. I get heated at this point thinking that Dell sent me a bad card. Before I call I decide to try the new card in my roomates computer, it WORKS with no problem....now I'm confused. I then pop the card into my girlfriends computer and same problem as mine, the card is seen in both Vista and Ubuntu Hardy but no networks are seen.
I decide to try my old 1390 in my roomates computer and to my surprise it works as well.
Quick Summary:
My computer--Dell Inspiron 9400, Hardy XP, Dell 1390 and Dell 1490 are seen in both but no signal seen. Girlfriends Atheros card works fine
Girlfriends computer --Toshiba Satellite A135, Hardy Vista, Dell 1390 and Dell 1490 have same problem as in my system, Atheros works fine
Roomates computer -- Dell Vostro -- XP, Dell 1390 and Dell 1490 work with no problem at all
The only conclusion that I could reach was that Ubuntu's broadcom drivers screwed up both windows and Ubuntu....but I have NO idea how this could possibly happen. The only thing my girlfriends and my computer have in common is that they both have Ubuntu on it. How weird is this problem? At this point I am leaning towards just ordering the same Atheros card as hers (but it's pretty difficult to find an Atheros card.....if anyone knows where I can please let me know). I guess I can sell the Dell 1390 and 1490 with no real loss but I would like to have some input.
Thanks all, sorry for the length, had to explain it all

