Locked out of computer

pop-up message not letting me log onto my computer. Message reads, ( A problem is preventing Windows from accurately checking the license for this computer. Error Code 0x80090019. ) How can I fix this or at least get my files off the computer and start over? Thanks any help would be greatly appreaciated.

shut off the popup bloker and do a windows update if that dont work you may have to reformat

Have you tried restarting your computer in safe mode? If you need to know how just restart the computer and tap the F8 button on whatever splash screen precedes the windows splash screens. This logs you into windows with a limited amount of drivers. You can still move files in safe mode. As a last ditch thing you can reinstall windows and usually it won't overwrite files that are left on the hard-drive. This is done a number of different ways depending on the computer manufacturer. Funmail me if you want to clarify your issue and get some help.