I need to use the data analysis in Excel.

I cannot install it, due to windows installer error 1635.
I don't have the key:
HKEY_LOCAL_MACHINE\Software\Classes\Installer\Prod ucts\
DFAD2CEE8555CA04E8C905508C8F018E
so it is not that.
What else can it be ?
Thanks.
Janiv Ratson.