newsrc problem? also: marking articles UNread

Hi,

I have two separate questions.

The first is, occasionally I'll read a newsgroup until I've read all
the unread articles. Then the next time I start tin and look in that
newsgroup, there they are again. It's as though the .newsrc file is
getting set back to the old value, but I don't know how. As far as I
remember, I exited tin normally before this happened.

Is this a known problem?

The other question is, how do I mark an article *unread* once I have
read it? Is there a way to do this without editing the .newsrc file
directly? (I know, the above problem would solve this one. :) But I
want to choose which files get marked unread!)

Thanks,

Joyce
[email protected]