Thread from: http://social.msdn.microsoft.com/Forums/en-US/sharepointdevelopment/thread/a2c6bed0-eee1-4f9b-b468-fc57c2e45c16
<Where>
<And>
<Eq>...</Eq>
</And>
</Where>
This will throw the "One or more field types are not installed properly. Go to the list settings page to delete these field" exception.
Good code:
<Where>
<And>
<Eq>...</Eq>
<Eq>...</Eq>
</And>
</Where>
or
<Where>
<Eq>...</Eq>
</Where>
<Where>
<And>
<Eq>...</Eq>
</And>
</Where>
This will throw the "One or more field types are not installed properly. Go to the list settings page to delete these field" exception.
Good code:
<Where>
<And>
<Eq>...</Eq>
<Eq>...</Eq>
</And>
</Where>
or
<Where>
<Eq>...</Eq>
</Where>