This appears to be caused by one of several Windows updates released by Microsoft on 10/12/17.

We are currently evaluating this issue and will update this article when we have more information.

In the meantime, please try the following:
  1. Export to a .csv format instead
  2. Remove the last update for Microsoft Office from the affected workstation(s). Reported updates that have caused the error for some users:
    • KB4041678  for Windows 7
    • KB4041676  for Windows 10
    • KB4011181
    • KB4041691
NOTE: Microsoft has identified this as an issue with a recent update and are working to resolve it.
This is one article outlining potential workaround to the issue.  This issue affects all exports from .JET Database Engines, not just Blackbaud products.
Microsoft 
Note: We provide links to third-party websites in an effort to help you resolve your issue.  We are not responsible for the information on third-party websites and we cannot assist with implementing resolutions from these websites.