That is not the only problem they have - I have had a problem since the 19th of January, with a malformed (?) cookie that reports an error when one returns to MyMSN from a followed link (the message is "Your request could not be processed at this time, please refresh this page or try again later.").
Initially it happened irrespective of platform or browser used (FF on Linux and Vista, Opera and Konquerer as well as IE - 6 and 8). I duly reported it and received a ticket number.
Some digging around revealed that it was a cookie that caused the problem, as deleting all MyMSN cookies restored access again.
I gave feedback to MS about this as well. The following day it only afflicted FF on Linux - normal operation had been restored to all other browsers.
Some more digging revealed that it was a particular cookie called MUID that is the culprit, which I duly reported again. No further communication have since been received from MS and the problem still exists.
Curiously this whole problem started the same day FF announced the spike in downloads following the IE6 security disaster (http://www.theregister.co.uk/2010/01/20/opera_and_mozilla_download_uptick_post_ie_warnings/).
Coincidence, or retaliation? Mmmmmm....
One positive development though was that I finally weaned myself of MyMSN (only visited it once in a while as I monitor my Hotmail account for messages from a forum that I have belonged to for a long time), as GMail now picks up my Hotmail.
And if I can find a way to change my e-mail address in that forum without having to close my account and therefore lose my logon name (as there are no guarantees that I can re-register the same name again), I can finally close my Live account (which was foisted upon me) as well.