HTC Hero :: Exchange Sync Problems After ROM Update

I updated my HTC Hero yesterday with the new ROM for Orange handsets. After the update i went back and setup my Exchange ActiveSync settings on the phone, it all seemed to work ok. Initial sync downloaded my emails, contacts and calendar, I then went to change the schedule to 'As item arrives', which is how I normally have the phone set for push emails. I found that when i change this setting the phone is constantly syncing with the server, as soon as it completes a sync it will start syncing again. I left it for about 30 minutes doing this over a wireless connection thinking it might stop eventually, but it didn't.

I have tried deleting the account and setting it up again and also done another factory reset, but as soon as i select 'as item arrives' in the schedule then it does this.

This worked fine before the update, any ideas whats gone wrong? Is there anything i can do to so that the phone only syncs when there is new mail?