Each time I log onto my computer, a box appears stating:
"Reminder Your computer is Not Backed Up, Back up Your Files Online Today.. Free computer Backup Available..

How do I get rid of this box?

Right click on this box and see if it offers you a "delete" option. Another way is to delete "cookies".

I have had a lot of clients with this backup program.
It is a program that installs when you install certain downloaded programs.

It might be one of the programs that is preinstalled on your computer but chances are it is this Blue Backup Icon

Go to Control Panel -> Program and Features.
Uninstall this program and all toolbars as well. They just cause issues and freezes up your browsers.

Hope this
Helps

In order to get rid of the message box, you need to remove the application from which it is associated. Go in the control panel – Add/Remove Program and uninstall that application. This will solve the issue. If not, then you need to check for some malware, virus infection in your computer. Get some good antivirus like Immunet Plus, Kasperksy, Bitdefender, Avast, Avira etc and perform complete scan of your computer. Quarantine the detected threats. Hope this helps.