One might imagine that during the absence of Mudcat, someone might get desparate enough to do those Windows updates that weren't current?

Some of the recent Mickey$oft "security fixes" do change how IE handles cookies, even though the settings look the same as before. I would suspect that other browsers may have offered similar "fixes" since many of these changes are in response to fairly specific "threats."

If you've made some of those updates recently, your browser might continue to use an existing cookie, but refuse to accept (and retain) a new "permanent" one. Sometimes it seems willing to accept a "session" cookie only - which, of course, goes away as soon as you leave the site.

If you've done any recent updates, you may need to set permission to accept cookies from Mudcat.
In IE, you go into IE Tools, Internet Options, Privacy Tab, and click on the little "Edit" box at the bottom to tell it to accept cookies for this site.

Or, it may just be a rampant Cookie Monster at work.

John