Don't use the "Test Connection to QuickBooks" option as this function attempts a connection in a special way. Use VB Demo to first connect and:-

sp_optimizeupdatesync All

to do a "all tables" update sync.

There's no need to schedule a manual optimizer sync. QODBC will automatically re-sync with a new connection or each query depending on the optimizer settings. On top of that, it's rare to use every table, so only the tables you use will be optimized automatically by QODBC.

See: How do I setup the QODBC Optimizer? Where are the Optimizer options? and MS SQL Server 2000 Linked Server issue using the QODBC optimizer 

NOSYNC means don't resync with QuickBooks, so if you use the NOSYNC tag it will not run a resync operation for that query, however, when you update QODBC all the installation defaults get reinstated.

To work correctly you must first check that you are running QODBC v8.0.0.240 or higher (see: How can I get the latest version of QODBC? ) and then change your optimization settings to use the The start of every new connection (with "Load Updated Data" first) option and confirm that the Multi-Table Sync option has been disabled. If not, uncheck the Multi-Table Sync option as this is often defaulted on (checked) with QuickBooks Enterprise and the QODBC Enterprise Desktop Edition.

To force a resync of the customer table first, do:

SELECT Customer.Name, Customer.FullName, Customer.IsActive, Customer.ParentRefFullName, Customer.CustomerTypeRefFullName, Customer.SalesRepRefFullName, Customer.Balance, Customer.JobStatus
FROM Customer verify
WHERE (Customer.Sublevel=1)
ORDER BY Customer.Sublevel, Customer.Name

I am running a Java application that is using QODBC to connect to Quickbooks to update timesheet data.  We recently upgraded to Quickbooks 2008 and upgraded the driver as well to version 8.  We were initially able to get the driver to connect to Quickbooks automatically while the application is not running, and it has worked fine for the past couple weeks.  I recently had to make a change to the program and create a new build file.  I have not been able to get the Java application to run automatically without Quickbooks running as before.  I keep getting the same error:

"Error = 8004041d, This application is not allowed to log into this QuickBooks company data file automatically..."

The Java appication will work when the admin user logs into Quickbooks and grants permission to the Flexquarters driver when the Java application is run.  But we do not want to do this all the time.  I have run through the procedure to test the driver and the connection to the VB Demo application. 

I see the proposed solution below, After upgrading to QuickBooks 2006 or 2007, QODBC "auto-login" unattended mode no longer works? but deleting all our users and recreating them seems like an excessive amount of work to solve this problem.

I also see below the proposed solution to run: sp_optimizeupdatesync All. Is this related to the same issue? 

Granting permission to the FLEXquarters driver (QODBC) is a one off procedure for a given application and company file. Not to sure why you need to do this over and over again. Both permissions and unattended mode setup is unique to the company file (not QuickBooks), so if you set these things up and then copy in the company file from yesterday, then you have to start the setup again from scratch.

In existing company files, if you add a QuickBooks user you can get the deaded ""Error = 8004041d, This application is not allowed to log into this QuickBooks company data file automatically..." error again and you will need to delete all QuickBooks users, remove the FLEXquarters QODBC Driver from QuickBooks Integrated Application options, and setup the company file again from scratch, yet again.