...Or more specifically, is there anyone who owns a Rosetta 800 and uses the AES/EBU digital I/O?

I'm having a bit of an issue with mine (at least I think that it's my Rosetta)... everything works great for AD/DA converstion but when I go to use it for any digital I/O it just feedback's a 1k tone.

I'm using it with an X-Digi Mix card, connecting it to a Pro Tools TDM system (Mix 24). I have been trying to connect a Lexicon PCM 91 via AES/EBU (to use as an insert on an aux channel in Pro Tools) but whenever the the PCM 91 locks to the Rosetta it just squeals! I've tested the AES/EBU on a DAT machine as well but I get the same thing... and I feel like I've tried everything! (ie. swtiching I/O, clocking to the Lexicon, numerous configurations in Pro Tools, etc.)

What's going on here? Any suggestions?

Thanks everyone!