Hi tronixmart, the problem is not a bad key.. First of all, if you are using Win 7 Home Premium (as I am), Home Basic, or Starter, you will not have a Local Users and Groups option. It is only for Win 7 Ultimate, Professional, or Enterprise. Jennifer Zhan's second suggestion regarding the changing of 'This account' to 'Local system account' under the 'Log on' tab in the properties window of Office Software Protection Platform is better, but still not adequate. If you try this, as I did, and then manually start Office Software Protection Platform before continuing the Office 2010 installation from the point of error, you will receive a new surprise. The Error 1920 message goes away, but then it is replaced with an oh-so-descriptive dialogue box telling you that 'Microsoft Office 2010 installation encountered an error.'

Changing 'This account' to 'Local system account' is useless, because after the error described above, the system somehow reverts the log on selection for Office Software Protection Platform back to 'This account,' with 'Network service' selected by default. The better solution is to give the user account called 'Network service' full permissions for the appropriate folders and registry entries. Simply follow these instructions I found on another forum: In Windows Explorer: Right Click on the folder OfficeSoftwareProtection Platform from C: Program Files Common Files Microsoft Shared and Microsoft from C:Program data(hidden folder) Properties > Security > Edit > Add > Type Network Service > OK > Check the Full control box > Apply and OK. In Registry Editor (regedit.exe): Go to HKEY_CLASSES_ROOT AppID registry >Right Click on the folder > Permissions > Add > Type NETWORK SERVICE > OK > Check Full Control > Apply > OK This worked for me and many others with the same problem, and took mere minutes to do. Hi tronixmart, the problem is not a bad key.. First of all, if you are using Win 7 Home Premium (as I am), Home Basic, or Starter, you will not have a Local Users and Groups option. It is only for Win 7 Ultimate, Professional, or Enterprise.