Outlook 2010 Stops Receiving Email

I have a user that has Outlook 2010.  We have Exchange 2010 on premise.  Her email account continually stops updating and receiving emails.  If she hits Send/Receive - Update Folder it will pull in most of her messages but not all of them.  OWA has all her messages.  I have tried the following

1. File - Account Settings - Unchecked Cached mode and restarted Outlook Then checked Cached Mode and restarted Outlook.  -  This made her Inbox update for a night then issue returned.

2.  I renamed OST to .old and restarted Outlook.  This made the Inbox Update for a few hours then issue returned.

3.  I created a New Profile and started Outlook and let her Inbox rebuild and download messages.  This made the inbox receive messages for rest of the night then issue returned today.

4.  I checked Send/Receive group settings and made sure the "schedule " box is not checked and the send/receive f9 box is checked.

5.  Ive made sure her inbox is not full and reached capacity of our 2gb limit.  Her inbox is about 600MB.


Any Ideas?