Limitations when runnning Sysprep for WIN7

 

If you want to know more about Sysprep you can find more here http://technet.microsoft.com/en-us/library/dd744512(WS.10).aspx#ResettingWindowsActivation

There is a limit of 3 times a sysprep can run on a single computer if you do not use rearm option

If you anticipate running the Sysprep command multiple times on a single computer, you must use the SkipRearm setting in the Microsoft-Windows-Security-Licensing-SPP component to postpone resetting the activation clock. Because you can reset the activation clock only three times, if you run the Sysprep command multiple times on a computer, you might run out of activation clock resets. We recommend that you use the SkipRearm setting if you plan on running the Sysprep command multiple times on a computer.