If Drupal tells you from the modules page that an update is needed, and you click the link and it says everything is fine, click over to the Updates report page (admin/reports/updates) to get the full story. It will usually be something important: a module you installed that is no longer supported (which is why it both is "in need of updating" and at the same time has no updates are available).

See http://drupal.org/node/961060 for trying to fix this.