No connectivity or Limited connectivity

Hello friends,
Let me explain everything in details. I have 3 laptops. two have Xp and one has Visita.

Recently i took LAN internet connection and configured it on a Laptop[XP], everything was ok untill i connect Lan cable to my new Laptop[with Vista]. it is showing 'No connectivity or Limited connectivity'. I tried with manual IP settings but No Luck..!
Then again connected teh cable to old one[XP]...it started showing the same message 'No connectivity or Limited connectivity'. I got shoked no one hav internet now.

I talk to IS provider. he said there is some bounding problem. then he offered me manual IP settings with DNS and all.
then i were able to connect my old laptop[XP] again. he suggest me " Do not connect other Laptop because bounding settings are reset." but i don't belive becoz my friend connect his laptops like plug and play.

then i didn't connect it to any one.
but i bought my 3rd laptop..i want to update antivirus and all. so connect it..first it was showing "Limited connectivity" but after manual IP settings it start working.....BUT what the hell heppend is -- I am not able to connect my old one laptop[Xp].
I were already hands up with visita [laptop] but now XP[laptop 1st] too.
in other word...I could never connct to Vista one laptop..and now only able to connect new 3rd laptop [XP] not old one[ laptop is ok when i connect it into office net].

so Is there any thing that ..we can use one connection for one laptop..???
please help....


--- KD---