KMail: "Unable to complete LIST operation"

As KMail was my main reason for trialling Trinity, I'm really enjoying its proper and zippy performance. But just one 'fly in the ointment': Sometimes when requesting 'Fetch Mail' it comes back with this error that I have never seen before (KDE3 or 4): "'Invalid response from server: Unable to complete LIST operation" Googling for this shows there was an old bug report: https://bugs.kde.org/show_bug.cgi?id=127696 Until today it has always then worked with a repeat 'Fetch Mail', but today KMail just locked up. (So I re-booted into Mandriva 2010.2; it's KDE4 KMail did not complain when asked to Fetch Mail...) Why is this happening with Trinity's KMail? (On Mageia-2) -- /\/\aurice