DTS Package error

Hi,
I am using a DTS package to retrieve data from one set of tables /flat files and load into another set of tables. The package is scheduled to run daily. After the failur/success of every step I get an email notification.
But sometimes the package starts, i get the email notification for that ..and then the package never proceeds. Neither I get a failure message nor the success message for the next step. When i checked in the log files I got the attached file, with the error code
8004043B.

This package calls some other packages. But what I feel is that its not completing even the first step.Hence the child packages are not being called.

Please help!!!!Enable logging for this package, so that the error message will be recorded in the log file.

Try setting the "Execute on main package thread" option. Right-click the
task, Workflow Properties, Options tab.|||Are you calling an external VB executable through your DTS ?