I did a search on some old forum communication and found another person who had run into this same issue.  In their case the trash had the wrong permissions on it and QuickBooks was failing when trying to verify that the company file wasn't in the trash. QuickBooks couldn't read the trash folder.

Double click on the Trash can to open the Trash window.  With that window open and in the foreground choose File->Get Info.  At the bottom of the Trash Info window it will show you the permissions for the Trash.  It should have your logged in user set with Read & Write permission and everyone else with No Access.  If you don't have that reset it to be that way.  Let me know here if that was the issue.