We ran into an interesting issue this week where all reports at the site collection level within "Content Structure and Reports" stopped working. The log included the following error:
Query Execution threw SPException: The query cannot be completed because the number of lists in the query exceeded the allowable limit
10/10/2008 11:38:19.16 w3wp.exe (0x09F8) 0x07F8 CMS Site Management 622h
Unexpected SMReportsData GetQueryResults - Query Execution threw SPException: The query cannot be completed because the number of lists in the query
exceeded the allowable limit. For better results, limit the scope of the query to the current site or list or use a custom column index to help reduce the number of lists.
My esteemed colleague Carlos Fernandez uncovered the following fix...
The default lists limit for the query generated by these reports is a 1000, so running the reports at the site collection level caused SharePoint to exceed this amount when the site contained more than 1000 page libraries. Populating the CAML List Type with:
<Lists BaseType="1" MaxListsLimit="0"/>