When you try to run Acrobat Reader version 4.0, in Windows 2000, you may receive:
Acrobat Reader Failed to update the system registry. Please try using REGEDIT.Acrobat reader V4.0 requires that users have Set Value permission on the following registry keys, for each user that runs it:
For security reasons, Windows 2000 does not grant this permission by default.
To grant the permission, use Regedt32 / Security / Permissions.