Can't install the CWYW package doe Office 2008


I have office 2008 (SP1 - update 12.1.2) and Endnote XI. I have downloaded the .dmg file for CWYW update but when I try to intall the package I get this message: “Microsoft Word® is running.  Plese quit Word to run this installation.” (Yes, there is a mis-spelling there!) I get this message even when there are absolutely *no* programs running except the installer. I have restarted more than once and I have tried everything else I can think of - including re-installing Office - but nothing works. BTW, I have installed the update perfectly easily on a desktop Mac - it is only my MacBook that is causing the problem.

Can you help?