[Evolution] won't expunge/empty trash

[Carpet Nailz <carpetnailz researchintegration org>]

I keep getting an error message when I try to Empty Trash or Expunge
Folder. I also tried to reduce the size of a large folder by moving some
mail to a different folder and got the same kind of error message.

There are now about 175 emails in my Trash folder that won't go away.

What could be causing that and what should I do?

Thanks.