Hello, just confirming I have the same issue. It's been happening for a few days but I figured someone was moving something around and it would clear itself up.

Just to reiterate, the error I get is when I visit the (http://www.xmarksthescot.com) page and I click on my name on the right side where it says "Welcome, Lady M."

That page leads to here: http://www.xmarksthescot.com/member.php?u=11789

Which reads the following 404:
Not Found

The requested URL /member.php was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
I can get to my profile just fine from any other page, like the forum main page for example (http://www.xmarksthescot.com/forum/) Just not from the actual (http://www.xmarksthescot.com)

Thanks for looking into it!