Windows XP Activation issues

Today during the process of trying to get my computer connected to my wifi after a power outage, I decided to restart my computer. Upon restarting my computer windows says when I try to log onto any user
"A problem has prevented Windows from accurately checking the status of the license for this computer. To proceed your copy of Windows must be activated with Microsoft."
When I click "Activate now" it takes me to a picture of my desktop and then stops loading so I cannot access task manager or start menu. The last time I even changed anything in my computer was about 4-5 months ago and since then I have never had this issue through all the restarts so I do not believe hardware changes to be the cause. Please help.