Hello HolyChipmunk please send me a PM with your Minecraft name.
@Server status :
I tried to fix the corrupted chunk. It's located on the Purple line between S-Station and OPLV. It's not just minecarts which have an effect on it, even if you walk through the area it will crash the server. I rolled back the server to 1.5 to see if it was 1.6 bug, and if it could be rectified by travelling through it again in 1.5 and then updating. Well it is 1.6 bug, and travelling through it in 1.5 didn't cure it in 1.6, so for now it's best just to avoid the area all together, until I can work out a way to sort it. It may well mean deleting the chunk in MCedit, but i've read that even that may not guarentee a cure. It's an artifact of the map generation getting poorer as people move further and further from the spawn point.
TL;DR: it's up on 1.6.5 again, don't use the Purple Line from S-Station to OPLV.