iphone 3GS inconsistently 'undeleted' deleted messages

All of a sudden, items inthe inbox for one email account would not delete (earthlink/mindspring.com). I have not done any upgrades, or mods to the phone. Haven't even dropped it . Then it allowed one item to delete, then another one -- then resumed to not letting anything delete. It did allow me to 'move to the trash folder, but only one at a time. Eventually, this stopped and the message references something about 'orphaned items'.
It then presented itself in my other email account (verizon.net) for about 3 deletes, then iit started to work properly for several hours, the it started to happen again. Off and on. Will work for a few, then not at all. The two accounts i have are pop mail - for spring mail (Earthlink) and Verizon. I have changed settings back and forth in hopes this would help it 'right itself' but no joy. I shut down the phone overnight and woke up to the same problem and a couple new ones:

1) when you go to select the items to be deleted, it times out. I click on Edit and start checkmarking my items, and then the edit undoes itself and refuses to let me select anything.
2) from the Mailbox menu, where you can select which email to drill into, it keeps moving into the first email listed, and won't stay on the Mailbox menu AT ALL.
3) not able to move items to the trash from the edit menu, have to do pull up the email and move it indivudally...

Has anyone else experienced this and does anyone have any ideas on how to correct?

I see that this has been reported delete issues in the past, but what i am seeing doesn't quite fit into what has been reported, and it's not clear what steps i need to take.

any help would be greatly appreciated.