It sounds like you have an "Iarf" cookie that's holding you hostage.
If you go to Quick Links, and Log Out, and then while not hooked up to mudcat, delete any cookies that have mudcat in their name, you should be able to log back on (reset cookie) with whathever name you've got registered - assuming you remember how to spell it and what password/email addy you used when you set it up.
(Cookies are usually in C:\Windows\Cookies, you may have to set WinExplorer {View - Folder Options} to "show all" to see them)
If all else fails, a PM to Pene or Joe should get whatever help you need.