Windows authentification issues

[Behemoth-]

Hey, did anyone got this kind of issues recently ? Yesterday, my sister's called me and told me she had a message saying his copy of windows was not guenuine. I just started my Main desktop and it says that I do not have a valid version of windows and ask my to buy a key. The wallpaper did not disapear yet though.. and I'm almost afraid of booting my laptop -.-
all 3 install are different oem keys (2x 32 1x64)... my desktop was running fine, I installed win7 on it like... past november.. and installed my sister's laptop ~2 weeks ago. I'll give my big friend Microsoft a friendly call shortly.. but it kinda screw me up...