This error indicates a corruption in the log tracking database table. In general, each profile will have a log tracking table that keeps track of which logs have already been processed. This keeps Urchin from duplicating data by processing log files more than once.
This table can get corrupted if processing is stopped or killed. Urchin 4.1 now includes a soft close function which should help in some cases. But on Windows, especially, clicking the "stop" button on a job is likely to corrupt the log tracking and possibly the overall data for this profile as well.
To fix this problem, you will need to delete the log tracking table from this profile. Within the Urchin installation folder, there should be a data/reports/(profile name) folder which contains the data for the profile. Make a backup of the data. Then, delete the files whose names begin with "ldata". This will delete the log tracking table from the profile.
When continuing to run this profile, be sure not to process log files that have already been processed as Urchin will not be able to tell.
If there is also corruption with the main database, please see the article on "Database hard close and data recovery using the udb- sanitizer" in the Knowledgebase by searching for "sanitizer". You may have to delete the data for the corrupted month.