just had a second one happen to me too.  luckily it was backed up in reviewed status from the night before, but this is very concerning.

Update:  I found this other article about a problem when saving that could be caused by the Antivirus: https://proconnect.intuit.com/community/file-actions/help/error-opening-client-cannot-locate-file-wo...

I did find it as a temp file in my directory, but it does not have the latest update indicating the e-file was successful like what shows in homebase where is shows EF Accepted.  The status in the temp one shows the status of "Review Done".  It does not show the e-file info.