This problem can be caused either by the servers of your email service or by your web browser. If it is caused by their servers, all you can do is to wait. If your browser is responsible for this error, press the Alt key and select Internet Options from the Tools menu. Open the Privacy tab and then uncheck the box next to Turn on Pop-up Blocker:
If this doesn't help, try using another web browser from Software Informer database. Also, you can try resetting the Internet Explorer settings.