Linux version 2.6.9-gentoo-r4 (64bit)

we are running postfix and using IMAP to access emails (kontact as the client)

Basically to quote a user...
"sometimes I get duplicate e-mail then once I have read them they both change into blank e-mails saying subject unknown sender unknown."

Sometimes a user can open up Kontact and all emails will be sender unknown and subject unknown.

I've tried googling for this and havent had any luck (the general answer is make use the /tmp partition isnt filling up, but this isnt partitioned separately)

any clues?

cheers