Fortunately this problem did not occur on all machines, however about 20%-30% of Windows 7 machines appeared to be affected.
There is no obvious pattern to which machines are affected and which are not. All machines are fully patched Windows 7 Ultimate with Office 2010. The symptoms are that when an Excel based report is run. The Ava print module traps the operating system error with the message "Excel has been manually controlled". Actually this message has stood us in good stead for around seven or eight years. However the Microsoft patch causing the issue caused the same symptoms.
The solution is simple once you know how.