How to reproduce:
1. Create empty project file
2. Take any audio file (or generate one) and change file Created Date to greater than your actual Date is
(for example your date 2017-09-15 12:00. Change it to 2017-09-15 18:00 )
3. Try to import file into Unity

Actual result: Error appears "Unspecified error during import of AudioClip Assets/"FileName"."FileFormat"
UnityEditorInternal.InternalEditorUtility:ProjectWindowDrag(HierarchyProperty, Boolean)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)"

Reproduced with: 5.5.4f1, 5.6.3p3, 2017.1.1p2, 2017.2.0b11, 2017.3.0b1

Workaround: Edit audio Created Date to the actual or lower Date and Time