Internet disconnects/ Local only/ IP adress problem

Very very confusing problem...

I have my HP Pavilion with WiFi Link 5100
I dont know what happened that somehow the internet connection disappears and stays "local only"

I have 4 computers connected to my network
2 Pc (wired)
2 notebooks (wireless)
.. mine is the only one that has that issue

... after trying to resolve the problem, it starts appearing a notification in my Windows XP pc ... "IP problem on your network".

I got so angry and try to connect my friend`s laptop to my network and search the web for a solution, but, the internet connection disappeared too!! omg

Please Help!