How to Fix an HTTP 400 Bad Request Error
Web browsers display error messages if they cannot load the page. If you get an "HTTP 400 Bad Request" error message, the reason is probably because the URL you are trying to visit has another set of "HTTPs." For example, it might say, "http://homepage/folder/page1.aspx/http://www.webpage.com." The error can also show up if you are using special characters. The Windows Service Pack for the .NET Framework can also help fix this problem.
Go to the Microsoft Download Center and download the .NET Framework 1.1 Service Pack 1 (see Resources).
Save the file and double-click on it when it completes the downloading process. Follow any instructions on the screen to install it.
Go to "Start" > "Run" and type in the command "regedit." Wait for the Registry Editor to load.
Go to "Edit" > "Find." Type "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ASP.NET" and press "Enter."
Right-click on the file name "VerificationCompatibility" when it loads. Select "Modify."
Type "1" for the "ValueData" and press "OK."
Close the windows and restart your PC.