We did contact EasyAcct.  The only suggestion they could give us was to run the Data File/Index Repair.  We have resorted to running a payroll journal after each payroll is posted and comparing for dropped checks, and then running the repair if drops are detected.  We do run a second payroll journal afterward to be certain the drops were added back.  So far, it has worked every time.  Hopefully at some point they will be able to figure out what is causing it and fix it.