Unable to view Custom Object
Second is your user could hide it on the page layout?
Spring '10 introduces enhanced security for custom object permissions. In Enterprise, Unlimited, and Developer Editions, when you create a custom object, the “Read,” “Create,” “Edit,” “Delete,” “View All,” and “Modify All” permissions for that object are disabled for any profiles in which “View All Data” or “Modify All Data” is disabled.
This ensures that all users don't immediately get full access to custom objects.
You can change these permissions in custom profiles, but not standard profiles. That is, users with standard profiles (except System Administrator) can't access new custom objects—you must assign them custom profiles and edit the profiles.To enable
access to custom objects, do one of the following: