thanks.
We're having Sungard's remote hands doing some testing to isolate fault.
There's a media converter between PE & CE, so I'm hoping that's not the source of the errors.
That BlackBox miniature media converter was indeed the source of the errors.
After we replaced it w/ a more serious model, all errors went away.
http://www.omnitron-systems.com/products/8380_10100_iconverter.php