If you have Service Pack 3 for SharePoint Server 2007 installed, and you try to install this cumulative update package, you may encounter an error that states that "the expected version of the product was not found on the system." If this issue occurs, run the package executable (.exe) file at a command prompt and set the PACKAGE.BYPASS.DETECTION.CHECK=1 switch to the following setting.
For x86: "office-kb2596986-fullfile-x86-glb.exe PACKAGE.BYPASS.DETECTION.CHECK=1"
For x64: "office-kb2596986-fullfile-x64-glb.exe PACKAGE.BYPASS.DETECTION.CHECK=1"
Héctor Calvarro Martín. SharePoint Dev. Microsoft Support Engineer for DEV EMEA