SPDIF issue: Keep losing Connection and Missing a Page in Setup> Hardware

[Baritonealone]

Hi,

My set up is

MAC PRO 4 core
OS 10.4.8
4 Gb RAM
PT LE 7.3.1
002 R

I have set up an effects return using the RCA SPDIF connections. I have noticed of a period of time that the 'return' can be extremly buggy. The issue being that at periods best know to itself no audio will come back from the unit ( a tc electronics gmajor) although audio is being received. It is not an intermittent problem during playback but a complete ceasing of all audio for whole days and then if by magic it will return and all will be fine.

I checked the manual and saw the reference to setting RCA = S/PDIF.

I looked for this and can only see everything else (eg changing optical format, clock etc) but NOT this function.

Should it be here. If it should, would this explain all the problems I am having.

Cheers