What exact version of NX ?
Try open the assembly Structure Only, and then from the assembly navigator open the components.
If that crashes, close everything, repeat but now open the "lower half" of the components. If this works, the problem is somewhere in the "upper half", try open the next 1/4 of the non-open components etc to find the problematic component.
Open all components fully, then run Part cleanup. Save
Do you synchronize Assembly Arrangements between NX and TC ?
Try turn off this and then try open the assembly.
Regards,
Tomas