Me too >>
Just installed dual CIVA in CS Captain (FSX) B727-100.
It aligned and worked perfectly for about 3 waypoints
into the flight and then suddenly quit (shut off). The yellow battery
light on the CDUs appeared when I started to taxi and would go out
when power was reduced and or brakes applied.  After takeoff
this light stayed on constantly until about 3 waypoints (30nm)
and then the CDUs' red warning lights came on and very shortly
thereafter the CIVA system shut down. Anyone have any
idea what I may have missed?
 FYI, I use FSUIPC payware with infinite battery enabled. Also double
checked the generator switches and power switch settings.  Even tried
turning the APU back on and giving it the load (with appropriate power
switch settings).  Recycled the main battery switch (on engineers panel).  
Nothing I tried made the yellow CDU battery light even blink.
 Haven't tried everything mentioned early in this thread.  Especially
should try starting up default Cessna, etc. first.  I'll follow up later
but in meantime I'm open for any tips.  I love the CIVA system >
used it with great success for several years with the (FS9) RFP B742.
Also trained on this system and worked on it for several years
in late 1960's as installed in the US Navy's SH-3D Helo.
 I tried to "insert" a screen cap for illustration but the insert
function here doesn't appear to work for me.
Thank you,
Ken