Hi Gerry,
I'm not sure, it sounds like the response from Fidelity isn't as expected by FM. If the problem persists still could you email me your log files (ofxretr.txt, ofxpost.txt, and xmldump.txt) after a failed retrieve? I'll take a look. For help on finding the log files, see the bottom of this page:
http://www.fundmanagersoftware.com/tintrtv.html
Also, are you retrieving from Fidelity NetBenefits, or Fidelity Investments? I just tested an account with Fidelity NetBenefits, and it was working properly.