While installing certain softwares you may recieve an "1402-Could
not open key" error message.This is caused by missing write permissions
on a specific key required by the program you wan to install.
Normally the error message informs you which key is affected.I had this
problem many times while installing Adobe Reader 7 as packaged software
from a third party.The write permissions were missing under CLASSES for
some certain keys.When running the installer package at the end
(of course :) ) the whole installation started to roll back and no Adobe Reader
has been installed.I found an 1402 event in the event log pointing to a
specific key and missing permissions.After i fixed the permissions for this
key and started over with the install the same happened again.The eventlog
showed the same event just pointing now to another registry key.So i gave the
necessary write permissions to the whole CLASSES key.After that Adobe
Reader 7 installed fine.The same issue may occure by other application
installations also.I suggest first give full permissions to the mentioned key
in the error message.If this does not work,give permissions to all keys
under CLASSES related to the application you want to install.If this still does
not work apply full permissions to the whole CLASSES hive and inherit them.
To do so follow the steps below.Navigate to :

- HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\

Right click now the Classes key and click permissions.Choose the name of the
user under which profile you install the application.Give this user full controll
(tick it in).