Internet Browsers Not Connecting to Network

This problem arose after a small batch of Windows Updates had been applied as routine operations. Any internet browser program e.g. IE, Chrome, Firefox, Opera would report "Network Unavailable". Unable to connect to the router on 192.168.1.1 using a browser either. Other network programs e.g. FTP, uTorrent, ping to router and ping to google.com all working ok so it was not a generic network connectivity promlem. This had to be something specific to the HTTP protocol. Symptom consistent with blocking of tcp port 80 so inspected Windows Firewall rules for any anomaly - none found. Temporarily disabled firewall (unplugged DSL connection first for safety due to reasonable paranoia about such things) and problem persisted, so this eliminated any issue with the firewall. Malware scans all clean. Rebooting did not clear the problem. Used System Restore to roll-back to the time just before the Windows Updates had been applied and this cleared the problem. Reapplied updates manually and no problem apparent after that. I did not "get to the bottom" of this one, but the fix using System Restore worked well enough! The System Restore utility is truly a life-saver at times.