The newsreader side of Windows Mail has problems with News Server who host
many thousands of newsgroups. Most users have reported they cannot
download a complete list no matter how long they wait. It's a bug and
hopefully it will be fixed before too long. In the interim, if you know
both the name of the news server and the complete name of the newsgroup,
you can always create a subscription by going to the newsgroup via a link
and when exiting, it will ask if you want to subscribe.
As an example, to connect to a newsgroup (even with Windows Mail or
Outlook Express closed) you would just enter a link in the following
format:
news://nameofnewsserver/nameofnewsgroup (with no spaces).