CAML error: "One or more field types are not installed properly."

Question

I'm using the U2U CAML Query Builder tool and no matter what I do, I can't create a query. It keeps generating the error: One or more field types are not installed properly. Go to the list settings page to delete these fields.0x81020014

If I just right-click on the list and do GetListItems, it works fine and returns results. By the way, it even throws the error when trying to create a query with the built-in Announcements list. Any ideas on what might be wrong?

Here's a sample one for the Announcements list that also throws the same error:

<Query>
   <Where>
      <Or>
         <IsNotNull>
            <FieldRef Name='Title' />
         </IsNotNull>
      </Or>
   </Where>
</Query>
<ViewFields>
   <FieldRef Name='ID' />
   <FieldRef Name='Title' />
   <FieldRef Name='Modified' />
   <FieldRef Name='Created' />
   <FieldRef Name='Author' />
   <FieldRef Name='Editor' />
   <FieldRef Name='_UIVersionString' />
   <FieldRef Name='Attachments' />
   <FieldRef Name='Body' />
   <FieldRef Name='Expires' />
</ViewFields>
<QueryOptions />

Answer 1

Remove the <or> or add a second clause to the <or>. In SharePoint CAML-queries you must have two (and only two) clauses in an <or> or <and> section.

In the U2U-Camlbuilder you can generate it like this: (Notice that filter is selected )

Answer 2

I think that you should remove < Or > tag or add the second fild to the expression