I wonder if it could be due to Windows 7 support ending over 15 months ago. This means that the OS is 'falling behind' Office 2013 (which is still receiving updates) and the compatibility 'gap' is increasing with time. It might explain why you see the problem getting worse. If this is the case then there is no answer except to upgrade the OS. This can be done free. See How to Upgrade to Windows 10 From Windows 7 for Free .