iTunes do not connect to iTunes Store anymore
I found the solution here


  Try this folks - it has just solved my problem - iTunes 10.5 is
  running perfectly and only using about 50% CPU.
  
  Start --> Programs --> Accessories (Right Click on Command Prompt) -->
  Run as Administrator then type in: Netsh winsock reset Hit enter,
  restart PC, open iTunes, go to Store
  
  Alternatively you can use the 'Run' icon just to the right of 'All
  Programs' when you click on start, past in Netsh winsock reset and
  enter.
  
  Hopefully it works for you too.
  
  For further reference material on this have a look at:
  http://support.microsoft.com/kb/299357