What is the value of N in your case?
Does the show query issue for that query go away if you change:
Code:
SELECT ip_address from
To:
?
This query is located in: admin/includes/classes/class.admin.zcObserverLogWriterDatabase.php at line 56. Hmm, in version 1.5.8, but you don't declare what version you are or were using...
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