question : loudspeaker driver 3D model

Hi, Sorry for my bad English.

I'm studying library sample loudspeaker driver(comsol 4.3b).
I want to analysis it by changing 2D model into 3D.

I used the same Model libary of the BCs(Boundary Conditions)
ex) The coil is driven with a body load set to
linper(V0)+coil_av(acsl.u_tZ*mf.Br*2*pi*r*N0)
2D : mf.Br, --> 3D : mf.By changed

But when I try to solve this problem, comsol solver show me the error in below.
" Out of memory during assembly "
What does this error mean??

I am using xeon E5 2640 2.5GHz x2, 128GB ECC Ram with win7 64bit

I wonder if there is a BCs setting that has to be modified when 2D is converted into 3D.

Thank you for any help.