Try deactivating all plugins and check to see if this resolves the problem. And, yes, I do realise that could be a real pain for you to do via the Admin interface.
You could deactivate the lot by using FTP, or your host's control panel, to rename your
wp-content/plugins folder to
wp-content/plugins-hold. Then create an empty
wp-content/plugins folder. Once you’ve logged in to your WordPress administration menus, use the same method to delete the empty plugins folder and rename
plugins-hold back to
If it deactivating the plugins does resolve the problem, activate the plugins one by one - checking the problem links/operations after each re-activation - until you find the problematic plugin(s).