It's hard to diagnose what the problem could be here. Did you look at the dump file? That usually helps.
I would look at the bond, angle, dihedral coefficients that you've specified. I'm not sure what potential you are using, but it seems odd (to me) that there are no bond, angle or dihedral coefficients defined for Si-O interactions.
Also, the temperature of the system is far below that of what you specified it to be, which is an indication that something is wrong well before the run ended. I usually encounter this kind of error when the system is far from equilibrium and atoms are flying out of the simulation box.