Magento Backend requires refresh to see any changes

Question

I'm having an issue with out Magento backend (Admin panel) whereby it requires a refresh to see any changes. I thought it might be a simple cache/index problem, but after flushing/reindexing the problem still occurs.

Even weirder, there haven't been any code changes in since this started occurring.

To give a better idea of what's going on, here's an example.

1. Log in, click on 'Sales' tab to show orders.
2. Navigate to another page
3. New order comes in
4. Click on orders tab, order does not show up.
5. Refresh page, order shows up.

Has anyone had a similar experience? Any ideas what might cause it?

Thanks!