CST memory exception error for nanosize structure

Dear all
I tried to simulate nanoscale (50nm) microstrip line in CST for the S-parameters at 100 GHz range. i ended up getting this message, port memory exception. Is it because the mesh size is too small? I have tried to optimize the size but i want to at less maintain 4 mesh at transverse direction.....
Can anyone explain to me what can be the problem?
thank you
HSU

What is the number of mesh cells that you are using for the entire problem? You may not have enough memory ram on you computer.