Import Patch Data for Windows fails; "Unable to cast object of type" error

Hi all.

We're running ITMS 7.5 SP1 HF5, and when I try to run the Import Patch Data for Windows task with "Delete previously downloaded data for vendors, software and languages that are now excluded" checked, the task fails after a few minutes. In the log viewer on the NS, I find this error every time:

Exception occured while executing task c27dbb50-6ddf-4125-87c1-d8f5b588491d.
Unable to cast object of type 'Altiris.SoftwareManagement.Resources.SoftwareUpdateResource' to type 'Altiris.PatchManagementCore.Resources.PatchSoftwareUpdateResource'.
   [System.InvalidCastException @ Altiris.PatchManagementCore]
   at Altiris.PatchManagementCore.Tasks.Server.PMResourceImportTask.RemoveSWUpdatesBasedOnExcludedSWReleases()
   at Altiris.PatchManagementCore.Tasks.Server.PMResourceImportTask.ExecuteTask(IServerTaskExecutionInstance instance)

Exception logged from: 
   at Altiris.Diagnostics.Logging.EventLog.ReportException(Int32 severity, String strMessage, String category, Exception exception, String footer)
   at Altiris.NS.Logging.EventLog.ReportException(Int32 severity, String strMessage, String category, Exception exception)
   at Altiris.PatchManagementCore.Tasks.Server.PMResourceImportTask.ExecuteTask(IServerTaskExecutionInstance instance)
   at Altiris.PatchManagementCore.Tasks.Server.PMResourceImportTask.OnExecuteSingleton(IServerTaskExecutionInstance i)
   at Altiris.PatchManagementCore.Tasks.Server.SerializingBaseSingletonServerTask`2.OnExecute(IServerTaskExecutionInstance i)
   at Altiris.TaskManagement.ServerTasks.BaseServerTask.Execute(ITaskExecutionEngine engine, IBaseTaskExecutionInstance instance, TaskInstanceRequest request)
   at Altiris.TaskManagement.Common.Execution.Engine.TaskEngineExecutionThread.ExecuteTaskHandler()
   at Altiris.TaskManagement.ServerTasks.ServerTaskExecutionThread.ExecuteTaskHandler()
   at Altiris.TaskManagement.Common.Execution.Engine.TaskEngineExecutionThread.OnExecute(Object eventComplete)
   at System.Threading.ExecutionContext.runTryCode(Object userData)
   at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart(Object obj)

**CEDUrlStart** :http://entced.symantec.com/entt?product=SMP&version=7.5.3153.0&language=en&module=zMiE8GTkwQc02UbYmAyY5fwnkHOyQgpchBpTk7a/nof1l9l8PMdbHCJPweJu1E43H7OYuCojZWqGJ5kITv9+Vw==&error=178960193&build=**CEDUrlEnd**

If I uncheck the "Delete previously" option, the import runs as expected; however, we're trying to flush out some patches for products that we're not managing anymore so we need to be able to use this option.

I did find TECH197686, which describes how to fix this problem in Patch Management 7.1 SP2 & MP1.x; however, the option to delete these items does not show up in the right-click menu in the report window, and my SQL-fu is not strong enough to attempt deleting these items through the SQL management console on my own.

Does anyone have any experience with fixing this issue that could lend some guidance?

Thanks!