[MOSS2007/WSSv3] Login box when a normal user logs on, but not with admin

[ISSUE]
A logon box constantly appears when a users is trying to log onto a SharePoint site. Whatever the user enters, he cannot get onto SharePoint.

[CAUSE]
The environment on which we experienced this behaviour was locked down according to security guidelines. One of these guidelines was to strip the "Read & Execute" permissions on the C:\Windows folder from the local users group. The .NET Framework requires Execute permissions on the C:\Windows directory to operate properly and because SharePoint relies on .NET, users were prompted for credentials.

[SOLUTION]
Add the Execute permissions for the Users group on the C:\Windows folder or restore the permissions on the C:\Windows directory to default:
- Open a command prompt.
- On a domain controller, run
secedit /configure /db c:\windows\temp\seceditsv.sdb /cfg "c:\windows\security\templates\DC security.inf" /log c:\windows\temp\seceditsv.log
- On a non-domain controller, run
secedit /configure /db c:\windows\temp\seceditsv.sdb /cfg "c:\windows\security\templates\setup security.inf" /log c:\windows\temp\seceditsv.log