http://www.rowand.myzen.co.uk/segs.zipmap29 - the living end
ACS scripts unloaded.
75 missing segs counted
The BSP needs to be rebuilt
I have rebuilt the nodes a number of times and still get the same problem. Neither Zdoom nor older versions of GZdoom (including r278) give me the message which leads me to think there is something up with the current GZdoom.
Either that, or there is something wrong with the map, but older GZdoom's and Zdoom don't pick it up.