admin/content/comment/approval -> 410 Gone error (linked from content -> comments -> unapproved comments) I have no idea when this happened (I've been trying to fix Mollom + PostgreSQL, to the point where I tried, and removed, some core patches), but when I go to Content / Comments / Unapproved Comments (which leads to admin/content/comment/approval) I get a 410 Gone error.

Was this supposed to be a view? How does one recreate such core views? Is the link the result of some module long since uninstalled?
You could try installing the module

admin_views

As well as converting core administration pages (admin/content/node, admin/people etc.. ) to use VBO, it will add a view to admin/content/comment/approval

Recommended.