Problem: lots of "expired articles"

[Lancelot appearing sideways]

Hi.  I use Gnus version 5.10.6.  When I open a large newsgroup
(rec.arts.sf.written, for example) I often run into the following
scenario: I get a list of threaded articles, with no "read" marks on
them, but when I select one the article receives a "G" and I get the
"article must be expired or cancelled" message.  This will happen for
whole sequences of articles, sometimes whole threads.  It's always the
oldest articles, so it's probably the articles _are_ cancelled.

Note that this happens regularly, even if I connect to the group and
then select an article right away; this isn't a matter of the
article's expiring in the meantime.

My question is, why isn't gnus figuring out that these articles are
cancelled, before showing them to me?

Any ideas?

/
:@-) Scott
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