I have 3 desktops all running Windows XP SP 3 connected to a ADSL Modem-Router. On 2 systems I have assigned static IP addresses and am not facing problems with Internet connection or LAN sharing. On the third system, if I assign static IP address then I am not able to visit ALL web sites. In particular I am unable to access an essential business portal. But if I use dynamic IP, then I am able to access all web sites required. But the problem with dynamic IP address is, I lose connection randomly (I get Limited or no connectivity error). I have to disable and enable my network adaptor to regain connectivity. Some times I have to repeat the procedure a few times or restart the system. I even tried to use a LAN card in place of the onboard LAN, but the problem continues. Some times I do not face any problem for 2 - 3 days and then suddenly, it surfaces. There are no proxy settings and I have tried different browsers like Firefox, Chrome, IE 8 etc. I am also using McAfee Security-as-a-Service.
Any suggestions?? Please do not suggest to upgrade the OS as my business software is not fully compatible to other versions of Windows as yet.