Hi I am using a custom made modpack and have come across a problem with your carriages and a mod called Project Red (PR).
When any of PRs wires and logic gates are moved using a carriage they will vanish once the carriage settles. Relogging does not seem to make them reappear and blocks can be placed as normal with no crashes.
The only exception to this is the Timer and State Cell, when they are moved by a carriage I crash.
So far I have only tested with Frame Carriages and a Carriage Engine.
If you need anything else then please ask.
Crashlogs:
https://dl.dropboxusercontent.com/u/44022905/RSIMnPR/ForgeModLoader-client-0.log
https://dl.dropboxusercontent.com/u/44022905/RSIMnPR/crash-2013-10-08_20.03.09-client.txt
Project Red Thread: http://www.minecraftforum.net/topic/1885652-forge-multipart-164-project-red-an-rp2-replacement-v40310-9302013/