Netbook (aspire One) Loses Internet Connection

I have a netbook (ASPIRE ONE) with windows XP SP3. When I am at the office the internet connection fails frequently. The internet connection icon disappears after few seconds. But the rest of the computers that are in the office work OK with the internet. But at home, my computer work well, even the internet icon appears and remains. At office, there is a belkin300N router. At home, I have the same model but old version.there are computers with Windows Vista or Windows XP either at office or at home.