Check that the 'Auto Refresh' check box is ticked at the top of the screen.
Once this is done select 'Settings' then 'Save settings' to ensure that this does not untick itself when restarting the application.
This may also be due to problems with your Internet connection. Most broadband lines are contended, they are shared with many users. This means that during certain periods where somebody else on your line is engaged in heavy use, it may slow down your connection. Also certain ISP's have usage limits and they may throttle or shape your traffic to restrict your usage at key times. You need to check your terms with your ISP to be certain.