The problem its that you install a program and the proxy settings changed
to fix it you need to reset the setting
to reset your proxy settings yourself, follow these steps:
On Windows XP, click Start, or on Windows Vista or Windows 7, click the windows buttom, and then click Run.
In the Run text box, copy (CTRL+C) and paste (CTRL+V) or type the following:
reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings" /v ProxyEnable /t REG_DWORD /d 0 /f
Click OK.
And again On Windows XP, click Start , or on Windows Vista or Windows 7, click the windows buttom, and then click Run.
In the Run text box, copy (CTRL+C) and paste (CTRL+V) or type the following:
reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings" /v ProxyServer /f
Click OK.
I had this problem today and i fixed it
hope its fix for u too