I installed the latest Kindle Previewer 3 and this is the error I get now:
calibre, version 4.3.0
ERROR: KFX conversion failed: <p><b>Cannot convert BOOK NAME</b><br><br><b>KFX creation error:</b> Invalid local symbol created: rsrc7
Invalid local symbol created: rsrcG
Invalid local symbol created: rsrc4V
Invalid local symbol created: rsrc5M
Invalid local symbol created: rsrc6E
Invalid local symbol created: rsrc78
Invalid local symbol created: rsrcSW
Invalid local symbol created: rsrc1M5
Invalid local symbol created: rsrc25B
Invalid local symbol created: rsrc2GP
Invalid local symbol created: rsrc2UV
Invalid local symbol created: rsrc2WP
Invalid local symbol created: rsrc2WW
Invalid local symbol created: rsrc2X2</p>