Greetings all.
I run Trainz 2010, and my primary route (London Wembley Yard\St Pancras to Lille in France, including HS1, LGV Nord, and the Channel Tunnel) has had to be operated in daylight hours only because of this problem - until I read this thread for some insight. I originally thought that the various sky textures I tried were the culprits causing the night crashes, but after reading this thread I figured out that it was caused by the headlight scripting used by the old TGV SE locos I use to power Eurostars - or more specifically the Eurostar style paintshed repaint of that model authored by "IckleTigress".
I worked out a solution that seems to work well if you can tolerate locos not using their headlights at night - not very realistic, but I am an operations oriented Trainzer, not a rivet counter. Add the rule called "Loco Lighting Control Rule" to your session, move it to the very top of the rule list, and change it's settings so that locos turn their lights on only during daylight hours, for example between 1000 and 1400 hours. Since doing this it hasn't crashed at night once. If you can tolerate the lack headlights in the wee hours, this solution might work for you.