DTS Problems - Error opening datafile: The system detected a possible attempt to compromise security.

One of my clients has a scheduled job that runs a DTS package every day.  Recently the job began failing.  I set up error logging on the DTS package, and have included the error below.

I have tried running the DTS package manually, and it worked fine.  I also manually started the SQL job, and it ran fine.  It only fails when the job runs automatically at it's scheduled time.  

The DTS package exports a file to a folder on a mapped network drive.  The connectivity between the local computer and the mapped network drive seems to by fine.

Around the same time that this started failing the in-house IT guy said that he removed some old/unused users from the network.  I noticed that one of those users was the owner of the DTS package and the SQL job.  I tried changing the owner to an admin user that I knew existed, but it still failed.  I also tried giving the "everyone" group full control permissions on the export folder.

Here's the error message recorded in the DTS log file...  Any help would be greatly appreciated. Thanks!

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The execution of the following DTS Package succeeded:

Package Name: DataQuickExport
Package Description: Compile and EMail DataQuick Request
Package ID: XXXXXX
Package Version: XXXXXX
Package Execution Lineage: XXXXXX
Executed On: XXXXXX
Executed By: XXXXXX
Execution Started: 8/14/2008 2:16:00 PM
Execution Completed: 8/14/2008 2:16:13 PM
Total Execution Time: 13.047 seconds

Package Steps execution information:


Step 'DTSStep_DTSDataPumpTask_1' failed

Step Error Source: Microsoft Data Transformation Services Flat File Rowset Provider
Step Error Description:Error opening datafile: The system detected a possible attempt to compromise security. Please ensure that you can contact the server that authenticated you.

Step Error code: 80004005
Step Error Help File:DTSFFile.hlp
Step Error Help Context ID:0

Step Execution Started: 8/14/2008 2:16:00 PM
Step Execution Completed: 8/14/2008 2:16:13 PM
Total Step Execution Time: 13.047 seconds
Progress count in Step: 0

Step 'DTSStep_DTSSendMailTask_1' was not executed

Step 'DTSStep_DTSActiveScriptTask_1' was not executed
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