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The problem with function getMetaTitle in view.php
Maybe the solution for your problem was found here.
Since that solution did not work in my magento installation I used the hook named ‘catalog_controller_product_init_before’ (new in 1.3.0) to set the default category to 1 (absolute root category) because this error occurs only if you follow a product link without category part (like recently viewed, compared and so on) when no LastVisitedCategoryId ca be recovered from the session.