Start by making sure you have the latest version of iTunes.
Check this Apple article out-> Apple software on Windows: May see performance issues and blank iTunes Store
If it's what you're seeing, you can try resetting Winsock as a temporary fix.
1. To do so, please do the following in an administrator user:
Windows Vista and Windows 7: Right click All Programs and choose Accessories > Command Prompt. Choose to open as an administrator.
Windows XP: Click Start > Run and type in cmd.
2. Enter the following command:
netsh winsock reset
3. Restart the computer and test the issue.
Note: If the issue returns, third-party software may be reinserting the LSP.