TCP/IP stack corruption problem.
1. Open Start Menu > Run, type cmd and press Enter
2. In the command prompt window, type netsh int ip reset c:\reset.log and press Enter
3. Restart your computer
Incorrectly set DNS server problem.
1. Right-click My Network Places on your desktop, select Properties. Right click on Local Area Connection and select Properties
2. In the listbox, double-click on Internet Protocol (TCP/IP). You would see a TCP/IP Properties window as shown above.
3. Select Obtain DNS server address automatically and save settings.
If this does not work, set DNS servers manually to the ones your ISP supplied or something like OpenDNS servers (220.127.116.11)
Open Start Menu > Run, type cmd and press Enter. In the command prompt window, type netsh winsock reset catalog
Try Winsock XP fix tool : click here
Also try to reset IE8 settings : click here