"Sorry, Bad Request!" Message

I keep getting the following message when I try to access certain sites on Yahoo:

Your browser sent a request that this server could not understand.

The request line contained invalid characters following the protocol string.

Please check the URL for proper spelling and capitalization. If you're having trouble locating a destination on Yahoo!, try visiting the Yahoo! home page or look through a list of Yahoo!'s online services. Also, you may find what you're looking for if you try searching below."

 I have done nothing different, and I have no idea why this is happening all of the sudden.  All help is much appreciated!