mismatch between summary lines in the summary buffer and articles they correspond to

[napofrog]

Hi,

I've recently started using gnus to read my email on an IMAP server.
I've just started getting a weird mismatch effect where sometimes the
information on a summary line in my main INBOX does not match the
article that gets chosen when I press SPACE with the cursor on that
line, but rather matches some other article (which generally should
have been split off into another group by my nnimap-split-rule).  Any
idea why this occurs, and how I could prevent it in the future?

Thanks!

roger levy