Strange New mail problem

[Dave Wood <dave@xxxxxxxxxxxxxxx>]

I have just imported all my mutt settings from my PC to my laptop.

Now a strange thing occurs:

I have new mail marked N
I go into mbox and read mail
I leave mbox - N is gone
I look into another mbox briefly and return to browser
N appears again for new mail

This also happens if for example I close mutt after reading mail, and then
restart it. Nothing I do will rid me of the N.

I've tried deleting the mbox and creating one from within mutt, and also
using touch to create and empty mbox.

I've checked the permissions on mboxes so they are rw'able.

Any ideas what I can check next?

-- 
It is better never to have been born.  But who among us has such luck?
One in a million, perhaps.