Remove wga notification

Hello,
Hello,
plz help me to remove window genuine notification error in "window 7", this shows " this copy of window is not genuine" and suddenly it turns the desktop into black colour. although I have tried the method given for "window XP" but it does not show Notify/WGALOGON folder inside the Winlogon folder. I have tried for "task manager/processing" but file "WgaTray.exe" is not found there. I have also tried for [ C:\Windows\System32\ and locate and delete WgaTray.exe ]as described above but "WgaTray.exe" file is not available in system 32.

if someone can help me , plz tell me the way to remove it. t is disturbing my research work.
i will appreciate the help from u.