There's a huge dialog box that appeared on my desktop yesterday. How do I get rid of it?

@,
 
Welcome to the Webroot Community!
 
We apologize for the issue that you are experiencing.
 
I was unable to locate an account with the email address provided.
 
For this issue the best thing to do would be to contact our support team so they can take a look and see what we can do to assist.
 
Please note that you must have a valid subscription to recieve our free support.
 
Support Number: 1-866-612-4227
Support Ticket: https://detail.webrootanywhere.com/servicewelcome.asp
 
Best Regards,
 
James G.
Webroot Community Support Team