Error, "error 400: validation failed" or "Unable to cast COM object of type 'MSScriptControl.Scri (4231225)

When running an automation script with some variables, I get the following in the output automation log:

error 400: Activity 'Set_Variable_4' validation failed: Set Var - 1: Variable value is not valid <variable_value>

<automation_name>.log: Variable value = Unable to cast COM object of type 'MSScriptControl.ScriptControlClass' to interface type 'MSScriptControl.IScriptControl'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{0E59F1D3-1FBE-11D0-8FF2-00A0D10038BC}' failed due to the following error: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)).