Multiple window issue *Edited

Edit:  It seems it is affecting most windows.  I can't open more than one window at a time.

Apologies if this has come up already today but I am having an issue with the bank feeds.  Usually I can keep the window open while I use other windows to enter the receipts and disbursements that are listed on the bank feed via sales and banking and other windows.  This morning it won't let me keep it open.  It keeps flashing like it does when the window that is open needs to be closed before moving into another window.  Rather annoying as I have to keep opening and closing it.  

Is it just me or has something been updated overnight and changed the way it works?  If it is an update it needs to be fixed.  It's just not practical.