How to Frease the UI from User so background thread can update UI ?

Use Case: User longed in and a table opened showing statuses of appointments. every row has a drop down (Combo Box) to change status (Scheduled, arrived, Reviewed). Now Multiple users has opened this table in their own browsers and making continuous changes to appointment status. These changes should be reflect on all opened Tables i.e If User A change status of appointment ap1 it reflects and refresh on all Tables currently opened).

So The solution i am thinking is to refresh table component continuously in every 1 mint. This Will Query database and reload the Table Container with updated Statuses. For This Purpose I uses Refresher add-on But their raises an exception i.e concurrent ModificationException . because some times user also changing the table component by changing combo statuses in table meanwhile refresher refresh the Table and their raises concurrent Modification exception. So I am thinking of Freezing Table component from User Point of View so user cant do any thing and in background can easily refresh table.

If For This Use Case You Guys have Better Solution please do tell me. I am grateful of you.

Using Vaadin 6.8.12, java 1.7, apache Tomcat 7.42