Problems logging on:

By far the most common cause for logging on issues where you enter your user name and password and get kicked back to this logon screen without an error is pop up blockers.

If you are using the pop up blocker built into Internet Explorer in Windows XP SP2, you must add this website to your Trusted Sites.

If there is a separate popup blocker in use - eg. as part of the Google or Yahoo toolbar - you must disable the popup blocker for the COWS site. If you don't know how to do this, you are much better off uninstalling the popup blocker / toolbar.

Alternatively, in the more common toolbar popup blockers, holding down the CTRL key when you click login will bypass the popup blocker. You may have difficulties with other popup windows used in COWS, however.