I am experiencing the same issue.  I was able to use the letter templates through Word feature back in January.  As a company and for cost savings, we decided to eliminate our other CRM software and use QB strictly for our customer correspondence.  We did mass amounts of manual data entry into QB to make this transition, and now we are unable to print letter is Word.  Super frustrating!  I have tried both rebuilding our data file and the ToolHub recommendations.  Word and QB are both up-to-date.  Nothing has worked to correct this issue.  QB please help!