Hello, this may not be the answer to your issue, but I had a similar problem with a small hp netbook. I had other computers in my home using my network and all got ip addresses and could go on the internet. This particular computer could do so for several months and then when I was about to sell it to my renter, it could not get an ip address and would report limited or no connectivity. I found the computer's mac address and made note of it and then using another of my computers, went into the router and saw that there was an ip address being handed you to that mac address but the hp netbook could not seem to see it. To compound the confusion, it would work ok on linix and would work on some wifi hotspots with no issues. Someone had me run some tests on the hp to see if there were any problems with my windows software which had to do with wifi and network and it came up with finding one of the dll files missing. I went to my other xp installation and copied the file over to the hp and that solved the problem. But I sitll an not sure how it would have windows connectivity in other places but not at my own network. No wonder I want to learn how to use linux more and more every day. I am sorry I cant recall which program I used to fine the network errors but maybe some one here can tell you. That may be the problem you are having. It might have been FSS.exe or systemlook.exe. I just cant recall now.
