Installation forbidden by "system policy" - why?

Hi, I'm running Windows 7 and get this message for every update/install/repair I do:

"This installation is forbidden by system policy. Contact your system administrator"

After som research I came across this solution:

"Browse the registry to HKLM\Software\Policies\Microsoft\Windows\Installer Create: DisableMSI Type: REG_DWORD value = 0 "

Other W7 users seemed happy with this solution but I can't seem to find a folder named "installer" on this path!?

Any help would be greatly apreciated! :)

If you're in a work environment the system admin probably set it up like that for there own protection.

Yes, but this is my home PC and I'm admin. The messages started appearing quite recently..

Create yourself a new administrator account.

Something changed your settings. Do you have user account control settings turned off ?

If its something that changed recently and you know when you can run a system restore.

I'll try a system restore... that should work :)