Copy of a previous post of mine the solution should run you:
It is a known effect that occurs after an upgrade (has happened with flash, for example) or after installing a program does not fully support.
The solution provided by Microsoft is this:
Start / Programs / Accessories / right mouse over sistems symbol >> Run as administrator.
There you give this command and hit Enter
slmgr / COLR
will parade a long litany of files on the screen. It is running the reinstatement of the license files.
Once finished go to Control Panel / System and see if Windows / appears on. If not, turn it on (Activate now).
Check now if your Windows is as legitimate
Only if that did not work need to reset the license: you return to run command prompt as administrator, give this command and hit Enter
slmgr / rearm
A window is displayed indicating that it has implemented and saying to restart.
Do that and when you have booted go to Control Panel / System and active again Windows 7.
With this your problem should be resolved.
PS: All commands have indicated are valid only for Windows 7. They should run on a Vista even if the same problem