|What have you tried in your firewall configuration, Internet Explorer options, and Command Prompt?|
Open up Network Connections (Start > Run > type: ncpa.cpl) and confirm the network adapter you're trying to use is connected and the properties of this device are proper for your network. Without more information about your network setup and settings, I cannot provide direct steps for remedy.
In addition, have you tried performing full system scans with your anti-malware programs already installed? Whenever there is an abrupt problem, I suggest scanning for malware.
Apologies if I don't respond to your reply immediately. I don't check this site daily, but you're welcome to PM me as a reminder.