14 May Error with Microsoft Office when computer wakes from standby/sleep
The problem appears to be that after the computer wakes from standby, MS Office attempts to access the network share before Windows has had time to properly reconnect it. The causes MS Office to show an error to the user.
The following KB article provides a good description of this problem and their suggested solution.
KB 2434898 : Word cannot establish a network connection error after you resume a computer from standby in Office Word 2007