Essential OSETUP.DLL for Smooth Running of Microsoft Office
Osetup.dll is an essential system component of the Microsoft Office 2007 Suite and is also known as the Office Setup Engine. The osetup.dll file can found in the Microsoft Common Files product. The default path for the osetup.dll is c:\program files\common files\microsoft shared\office 12\office setup controller\osetup.dll. The file is developed and published by the Microsoft Corporation.
During the beta release of Microsoft Office 2007, many users had issues with the osetup.dll file verification, where the digital signatures were not recognized when setting-up. The most experienced problem was an error message popping saying “X:\programname.WW\Osetup.DLL digital signature does not validate or is not present”. Initially thought to be a problem with the beta versions and illegal copies, the error became persistent even after the final release of Microsoft Office 2007. The “missing osetup.dll” error was appearing even when users were installing from a legitimate disk.
As the error appears immediately after inserting the disk in your CD/DVD drive for setup, there are two methods that might solve the problem.
1) Go to Start, Run and browse to the location where you have the CD i.e. Start, Run and D:\<path where you have the setup for project> | double click on setup.exe
2) Copy the CD contents to a network share and try installing in the local machine from the network.
As this is a problem with the digital signature of osetup.dll available in your current CD, downloading the dll file from a third party web source would not be very helpful. You may try that method initially, but it would be better to try setting up the Office Suite in several computers running Windows and check if it is only in your computer that the error comes up.
If the solution is evasive, you will have to contact Microsoft Tech Support.