This is a cookie problem. Scoop uses cookies to identify you with every page you request, so it knows what you are allowed to do. Generally this is caused by the cookie_host variable in your Apache configuration being wrong; it must match the domain you are using the access the site. See section 2.5.2 for more details.
Chances are you're being logged out. If you are, see the question above.
If you're still logged in but are being denied permission to do admin events, you should check the Groups Admin Tool (A.12) to make sure you actually do have permission to do what you're trying to do. If you've created another account, you may be logged in as that account and not the superuser account created when Scoop is first installed.
KeepAlive is on. Logging out waits for the KeepAlive to time out, a length of time set by the Apache directive KeepAliveTimeout. You can reduce the timeout or turn KeepAlive off entirely to speed up the logout process.
KeepAlive has some advantages, so you should read Apache's documentation on that directive and consider the advantages against the logout time issue to decide what you want to set the timeout to.
Users can request a new password from Scoop by putting their username into the login box and clicking the ``Mail Password'' button.
If the user does not have access anymore to the email address listed as their ``real email'' in their user preferences, you will have to change their password for them - but make sure to your satisfaction that they are who they claim they are! While logged into a Superuser level account, use the Edit User box in the Admin Tool box to type in their username, and click 'prefs'. Scroll down do where you can enter a new password for them. Type in a new password for them, into both boxes. Click ``Save'', let them know about their new password, and you're done.