Problem:
I have installed ARTEEditor for Sharepoint (MOSS 2007). For the site collection administrator user there is no problem using ARTEEditor, everything works fine. If any other user (Wiki Member = Contribute or Wiki Admin = Full Access) tries to edit the wiki page, ARTEEditor opens a login window and keeps asking for user/password, eventually failing.

Solution:
This error occurs when the ARTEeditor folder does not have the same permissions as the SharePoint Group your Site Collection Administrator is a member of. Navigate to the ARTEeditor folder within the Virtual Directory folder on your server that relates to your SharePoint application, right click to bring up the properties of the folder and make sure that the following groups are added under the security tab:

ADMINISTRATORS
WSS_ADMIN_WPG
WSS_WPG
IIS_WPG
AUTHENTICATED USERS (of the server with only Read permission)

And any other members or groups that are specific to your SharePoint application.

Try adding your user account to the “Policy For Web
Applications” screen. To do this, log in to Central Administrator and
select the Applications tab. Click “Policy For Web Applications”.
Click “Add Users”. Choose the right web application and All Zones.
Click Next. Choose your user account and make sure it resolves using
the People Picker. Give the account “Full Control” and click “Finish”.
You should be able to check files in and out using SharePoint Designer
without that annoying error message! Hope that helps

1. Backup the content database.
2. Backup the snap if its a virtual machine.
3. Lock the site.
Do not restart the web server after locking site. If you restart the server the site will be locked for everybody. You unlock by using step 7 and then do step 3 again.

At a command prompt on the drive on which SharePoint Products and Technologies is installed, change to the following directory: COMMONPROGRAMFILES%\Microsoft shared\Web server extensions\12\Bin.

To determine the current access level of the site, type the following command, and then press ENTER:

stsadm -o getsitelock -url

where URL name is the URL of the site collection that you want to back up.
If the current access level allows changes to the site content, change it to read-only by typing the following command, and then pressing ENTER:

stsadm -o setsitelock -url -lock readonly

where URL name is the URL of the site collection that you want to back up. For more information, see Setsitelock: Stsadm operation (Office SharePoint Server).
When the backup is complete, use this procedure to return access to the site collection to the original setting determined in step 1.

4. Backup the site collection.
On the drive on which SharePoint Products and Technologies is installed, change to the following directory: %COMMONPROGRAMFILES%\Microsoft shared\Web server extensions\12\Bin. Type the following command:

stsadm -o backup -url -filename [-overwrite]

where URL name is the URL of the site collection that you want to back up, and where \\server name\folder name\file name is the UNC path of the backup folder and the name of the file that you are backing up to. If there is an existing file for the backup, use the -overwrite parameter to overwrite the existing file.

If the backup is completed successfully, the Command Prompt window displays the following text:”Operation completed successfully.”

If the backup is not completed successfully, the Command Prompt window provides additional details about the failure. Most typically, an incorrect URL or file name was given.

5. Delete the site collection.
6. Restore the dat file.
To restore a site collection, type the following command, and then press ENTER:

stsadm -o restore -url -filename

where URL name is the URL of the site collection that you want to restore and UNC path is the UNC path of the backup shared folder.
When you receive a warning that all selected items will be overwritten, type y, and then press ENTER.
When prompted, type the user name and password for the Web application and content databases.

If the recovery is completed successfully, the Command Prompt window displays the following text:”Operation completed successfully.”
If the recovery is not completed successfully, the Command Prompt window provides additional details about the failure. Most typically, an incorrect URL or file name was given

7. Unlock the site.
To determine the current access level of the site, type the following command, and then press ENTER:

stsadm -o getsitelock -url

where URL name is the URL of the site collection that you want to back up. For more information, see Getsitelock: Stsadm operation (Office SharePoint Server).

If the current access level is too restrictive, change it by typing the following command, and then pressing ENTER:

stsadm -o setsitelock -url -lock none

where URL name is the URL of the site collection that you want to back up and Access Level is the site lock setting the site had before being backed up. For more information, see Setsitelock: Stsadm operation (Office SharePoint Server).

Reference:
http://technet.microsoft.com/en-us/library/cc706871.aspx
http://blogs.technet.com/josebda/archive/2006/10/03/Renaming-a-Site-Collection.aspx