6306 Class not registered

SYMPTOM

Previewing a custom form generates a Class not registered error.

CAUSE

There is an issue with Microsoft Word which must be repaired or reinstalled. 

RESOLUTION

Repair or reinstall Microsoft Word

1. Open Microsoft Word.
• For Office 2007/2010: Click the Microsoft Icon from the far left of the menu bar, click Word Options
• Select Resources.
• Click Diagnose.