Spelling did not complete properly. If this problem persists, notify your system administrator.

One of the many great new features in Microsoft Officer SharePoint Server (MOSS) 2007 is the ability to use spell check for any content you add to your site. One of the NOT so great new features of MOSS 2007 is the fact that this no longer works if you lock down your permissions on your server.
We recently locked down the permissions for ‘read only’ access users - essentially your viewers in the web site, which for me is any authenticated user. Unfortunately then the complaints started that when ever a user tried to do a spell check they got the error:
“Spelling did not complete properly. If this problem persists, notify your system administrator”

After some digging around it turned out that this is a permissions error. Turns out if you lock down permissions in SharePoint, user’s can no longer view the dictionary against which SharePoint does it’s spell check, and consequently it no longer works.

Thank to Microsoft as this is fixed with Service Pack 1.
Spell Check Permissions work around
You will need to modify the permissions of the Group to which the user has been added, in your case the user has been given Read Permissions.

1. Browse to the root site and go to “Site Actions”->”People and Groups”.
2. Click on “Site Permissions”
3. For the group (say “Visitors”) to which the user facing the problem has been added – find its “Permissions” level – it was “Read” in your case as checked during the last call.
4. Click on “Settings”->”Permissions Levels”
5. Click on “Read”
6. Check the 2 check boxes for “Browse Directories - Enumerate files and folders in a Web site using SharePoint Designer and Web DAV interfaces.” and “Use Remote Interfaces - Use SOAP, Web DAV, or SharePoint Designer interfaces to access the Web site.”.
7. Click on Submit and check if the issue reproduces.