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It is most likely because of some rogue blocks still being in the database even though the module has been uninstalled.
We've had reports of that happening as well as templates persisting after module uninstallation, but have trouble reproducing it.
For now, I would suggest that you manually look in your database (with phpmyadmin or similar tool) and see if there are records in the newblocks table that have "mid" values that are not present in the modules table. Then delete the records in the newblocks table and see if that corrects it.
We are very interested in getting PHP and/or MySQL debug information from the module uninstallation page from anyone experiencing this bug.
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Cusix Software