Could not register Nero on Win 7: Error Code 100

Hi all. I was trying to install Nero but I got this error message: “Unable to register C:Program FilesNeroNero7NeroShowTimeiHDRuntime.Code 100.” What could this be? I have two versions of Nero which are Version 7 and Version 8 and I tried installing both of them from different CD’s one at a time but I got the same error message. I am running Windows 7 Professional. How could I fix this? I need some suggestions. Let me know if someone had encountered this problem before.
