Invalid or Bad Proxy Server in Browser
Having your proxy settings tampered with is a common side-effect of viruses. Some viruses set proxy servers within the browser settings so the browser will reroute its connection through a made-up server. This blocks you from getting on the internet to download virus protection software, among other issues. When you experience a bad proxy server entered into your browser, it will show up as a connection error within the browser.
This commonly affects Internet Explorer and Firefox. If you are having trouble getting connected to the internet using a certain browser, then it's a good idea to check your proxy settings.
Possible problems
A browser may show a Page Cannot Be Displayed error when you try to access a website, but another browser on the same computer shows the website successfully.
Check for a proxy server in Internet Explorer
Go to Tools -> Internet Options.
Click the Connections tab.
Click LAN settings in the lower right of the pop-up window.
Check to make sure the option for Automatically detect settings is checked and NOTHING is checked in the Proxy Server section.
If there is something checked in the "proxy" portion of that window, remove the checkmark and make sure the Automatically detect settings box is checked above.
Click OK.
Click Apply if any changes were made or OK to exit the window.
Check for a proxy server in Firefox
Go to Tools -> Options.
Click Advanced icon on the top of the Options window.
Click the Network tab.
Click Settings.
Assure that No Proxy or Auto-detect proxy settings for this network is chosen (either of the two options are acceptable).
If Manual proxy configurations is selected, then change the selection to one of the two options listed above.
Check for a proxy server in Chrome
Click the Customize and control Google Chrome symbol (three horizontal lines or three vertical dots) to the right of the address bar.
From the drop-down menu, click Settings.
Scroll down to Network.
Note: If Network is not visible, click Show advance settings.Click Change proxy settings.
Click LAN settings in the lower right of the pop-up window.
Check to make sure the option for Automatically detect settings is checked and NOTHING is checked in the Proxy Server section.
If there is something checked in the "proxy" portion of that window, remove the check mark and make sure the Automatically detect settings box is checked above.
Click OK.
Click Apply if any changes were made or OK to exit the window.
Check for a proxy server in Safari
Click the Settings icon.
Click Preferences.
Click Advanced.
Click Change Settings next to Proxies.
Click LAN settings in the lower right of the pop-up window.
Check to make sure the option for Automatically detect settings is checked and NOTHING is checked in the Proxy Server section.
If there is something checked in the "proxy" portion of that window, remove the check mark and make sure the Automatically detect settings box is checked above.
Click OK.
Click Apply if any changes were made or OK to exit the window.
Important! Once you have removed the proxy settings from the browser, run another scan using virus protection software. Sometimes the proxy server entered will reroute the browser's connection to a server with a virus on the computer that will reinfect the computer again. If you remove the proxy settings then scan again, it will remove the possibility of reinfection occurring.
Didn't work?
Reboot your computer. If you still cannot access the internet, check your network connection. If necessary, contact your desk side support or take your computer to an ITS Service Center.