Problem upgrading Notes standard from 851 to FP4

I tried to upgrade Notes English standard from 851 to FP4 (with Administrator & Designer) on 3 different machines (Windows 2003 server).

All 3 failed with the same message :

“Notes hotfix did not install. Error encountered while installing Notes Core Hotfix component.”

Is there anything wrong with my platform ?

File is : lotus_notes851FP4_win.exe = IBM Lotus Notes Standard 8.5.1 Fix Pack 4 for Windows English(CZJA0EN)

Thanks for your comments.

Jean-Pierre Bloch