I’m running Windows 10. Is that a problem?

Yes.  The recent win10 anniversary update has stopped QB from working, unless you have 2015 or higher installed.

You are going to have to move up to a new version (2017 is out) on all win10 machines

Resolution for '2015 or higher issue: 'Attempting to use File Doctor and get this message: This file is in use. Enter a new name or close the file that’s open in another program. I’m using Quickbooks Pro 2014.' available: Yes.

The 2015 or higher issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the 2015 or higher issue yourself by looking for a resolution described in the article. If it is a complex 2015 or higher issue or you are unable to solve the issue, you may contact us by clicking here or by using other 2015 or higher support options.

For more information about resolving issues related to 2015 or higher in Quickbooks/QBO or to get support for the issue 'Attempting to use File Doctor and get this message: This file is in use. Enter a new name or close the file that’s open in another program. I’m using Quickbooks Pro 2014.', click the link below: