I did the following:

Opened Component Services,Expand Component Service->My Computer->DCOM Config, Locate “Microsoft SQL Server Integration Services 11.0” Rt click and select “Properties” Select the “Security” tab, In Launch and Activate Permissions, then “Edit” Grant “Local Launch”, “Local Activation” permissions for SQL Agent Service / proxy account MyDomain\MyAcct, Restarted SQL Agent and tried again.

Now the error in the event viewer is gone, but I still get the error in sysssislog: Source: Set FS File Parameters Script Task: Exception has been thrown by the target of an invocation.

What else needs to be changed?