I'm getting the above-mentioned error, but no suggestions seem to solve it. I still get it when deactivating all plugins and using Twenty Ten/Twelve/Thirteen themes.
Interestingly, it seems to only appear in instances where comments should be listed-- in the Recent Comments area on the admin dashboard (preventing the rest of the page from loading), on edit-comments, and on the edit-post page in the comments section.
I've optimized my database, and culled old comments, and nothing.
On the front-end, on my most recent post, comments aren't displaying (there should be 21 total). The site lists "21 comments" and just doesn't display them. They're in the database and the number 21 appears by the post title in admin.
Has anyone experienced this memory leak specific to comments?