Jane,
Thanks for the reply. Unfortunately, in my case the component field is not a link, it simply has "/Status/Perf" in text. I suppose that's the root of the problem, the event is somehow not being correctly assoicated with the interface.
My work-around has been to disable the threshold on the ethernetCsmacd/ethernetCsmacd_64 templates, which eliminates the event trigger. It would be nice to find the root cause, but it looks like the problem is limited to my deployment.
Larry