Email not staying 'Read'

[menos08642]

I've got a pop account set up on my 3G that is having problems. If I mark an email 'read' it stays 'read' for a little bit, but as soon as the phone checks email any email marked as 'read' goes back to 'unread'.
I've tried removing the email account and re-adding it without success. I have two email accounts on the phone, gmail via imap and this pop account. The gmail account does not have this problem.

Any ideas? I'm running JB 3.0 with no other mail or messages app installed.

---EDIT---

Well now it is doing it on the gmail account also.

 

[menos08642]

I've noticed that it only happens when the email is rather large (HTML email with a bunch of images). Also if I let the mail app sit at the email for several minutes until the data transfer icon in the top bar goes away, the email will stay read.