Microsoft has made available a Fix it solution to resolve issues associated with certain server connection errors that result in proxy servers being added to bad proxy list incorrectly, causing Internet Explorer to rotate through the specified list of proxy servers until all are temporarily disabled.
This issue occurs based on performance reasons, in the event that Internet Explorer cannot establish a connection to a proxy server, that proxy server is added to a list of bad proxy servers so that it is not reused for a period of time. By default, this period of time is 30 minutes.
If an automatic proxy configuration script returns a PROXY list that specifies multiple proxy servers, a connection to the next proxy in the list will be attempted. If that connection fails, then the process repeats until a connection is established or the list is exhausted. If the list is exhausted and no connection was established, the user will receive a “Page Cannot Be Displayed” error message in Internet Explorer.
To fix this issue, you can try these available workarounds;
Method 1: Restart Internet Explorer to clear the list of bad proxy servers.
Method 2: You can manually modify the registry by setting a custom-retry interval for bad proxy servers under the following registry key:
Create a DWORD value in this key named BadProxyExpiresTime, and assign a value of 0. This value is in seconds. Setting this value to 0 will prevent proxy servers from being added to the bad proxy list.
Important: Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Modify the registry at your own risk.
Alternatively, to fix this problem automatically, download and run Microsoft Fix it 50746 solution.