Okay, dumb question time. I know there's probably not enough information here to hazard a guess at the root cause, but here goes.
First thing first. I modded wolfram into my game, as well as cobalt and antimony. Wolfram is what we're focused on here.
Dwarven traders arrive. At first, the only thing I think is odd is that they have a Goblin Outpost Liaison with them. However, upon unpausing, something looked like it blew up. So, I quickly paused the game, and in their inventory notice "boiling wolfram" and "boiling black wolfram", among tons of other stuff. So, I have my wtf moment, unpause the game, get two more "explosions" and everything returns to normal. No one and nothing is killed, and the traders reach my depot safely. They are not carrying any wolfram of any kind.
The liaison has moved all of three squares over a month. When it's time for the traders to leave, they pack their stuff up, and the liaison rushes toward my fortress...and then the game crashes out.
For what it's worth, if I make any W/BW items in the fortress, there are no problems with them.
Here's Wolfram:
[INORGANIC:WOLFRAM]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL_SOLID:wolfram]
[STATE_NAME_ADJ:LIQUID:molten wolfram]
[STATE_NAME_ADJ:GAS:boiling wolfram]
[DISPLAY_COLOR:0:5:1]
[MATERIAL_VALUE:5]
[SPEC_HEAT:1000]
[MELTING_POINT:5000]
[BOILING_POINT:9000]
[SOLID_DENSITY:1000]
[LIQUID_DENSITY:2000]
[MOLAR_MASS:208980]
[IMPACT_YIELD:105000]
[IMPACT_FRACTURE:175000]
[IMPACT_STRAIN_AT_YIELD:3387]
[COMPRESSIVE_YIELD:105000]
[COMPRESSIVE_FRACTURE:175000]
[COMPRESSIVE_STRAIN_AT_YIELD:3387] 31
[TENSILE_YIELD:30000]
[TENSILE_FRACTURE:50000]
[TENSILE_STRAIN_AT_YIELD:94] 32
[TORSION_YIELD:30000]
[TORSION_FRACTURE:50000]
[TORSION_STRAIN_AT_YIELD:250]
[SHEAR_YIELD:1000000]
[SHEAR_FRACTURE:5000000]
[SHEAR_STRAIN_AT_YIELD:0]
[BENDING_YIELD:500000]
[BENDING_FRACTURE:500000]
[BENDING_STRAIN_AT_YIELD:0]
[MAX_EDGE:10000]
[ITEMS_WEAPON]
[ITEMS_WEAPON_RANGED]
[ITEMS_AMMO]
[ITEMS_DIGGER]
[ITEMS_ARMOR]
[ITEMS_HARD]
[ITEMS_METAL]
[ITEMS_BARRED]
[ITEMS_SCALED]
and Black Wolfram:
[INORGANIC:BLACK_WOLFRAM]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL_SOLID:black wolfram]
[STATE_NAME_ADJ:LIQUID:molten black wolfram]
[STATE_NAME_ADJ:GAS:boiling black wolfram]
[DISPLAY_COLOR:0:5:1]
[MATERIAL_VALUE:45]
[SPEC_HEAT:1000]
[MELTING_POINT:35000]
[BOILING_POINT:75000]
[SOLID_DENSITY:18000]
[LIQUID_DENSITY:20000]
[MOLAR_MASS:208980]
[IMPACT_YIELD:1005000]
[IMPACT_FRACTURE:1075000]
[IMPACT_STRAIN_AT_YIELD:30387]
[COMPRESSIVE_YIELD:1005000]
[COMPRESSIVE_FRACTURE:1075000]
[COMPRESSIVE_STRAIN_AT_YIELD:30387] 31
[TENSILE_YIELD:300000]
[TENSILE_FRACTURE:500000]
[TENSILE_STRAIN_AT_YIELD:904] 32
[TORSION_YIELD:300000]
[TORSION_FRACTURE:500000]
[TORSION_STRAIN_AT_YIELD:2050]
[SHEAR_YIELD:10000000]
[SHEAR_FRACTURE:50000000]
[SHEAR_STRAIN_AT_YIELD:0]
[BENDING_YIELD:5000000]
[BENDING_FRACTURE:5000000]
[BENDING_STRAIN_AT_YIELD:0]
[MAX_EDGE:100000]
[ITEMS_WEAPON]
[ITEMS_WEAPON_RANGED]
[ITEMS_AMMO]
[ITEMS_DIGGER]
[ITEMS_ARMOR]
[ITEMS_ANVIL]
[ITEMS_HARD]
[ITEMS_METAL]
[ITEMS_BARRED]
[ITEMS_SCALED]