The application that queries the Urchin database and produces each report, will time out if the data is not returned in under 45 seconds. If the database size is large enough, 45 seconds may not be long enough to retrieve all of the requested report data. When that happens, it simply times out and an error is typically displayed.
The time out value can be extended if you have sufficient access to the server that Urchin runs on.
Extending the Application Time Out