Try these one by one:
1) Where it says, "Go online to resolve....", do so, many a times that solves the issue.
2) In installed windows updates (look in left pane of Programs anf Features->View Installed updates), locate kb971033 (thats WAT), uninstall it, if it lets you. Reboot, then go to the microsoft genuine website and let it install WAT and validate.
3) Sudden random non genuineness can also be the result of a permissions issue in a registry key. Follow the steps here. Genuine Windows 7 Became Pirated? Make It Original and Activated Again - Tweaking with Vishal
4) If none of this works, download and run mgadiag.exe tool. http://go.microsoft.com/fwlink/?linkid=52012
Click on the Copy button, paste to notepad, save as text file and upload it here.
5) As a last resort, you call call MS. Activate Windows 7 by Phone