Well I didn't expect that my computer could be the issue.
I have enough disk space (100GB). I could definitely do with more ram, but some models run just fine (but gives inaccurate results).
I will try the restart trick for sure. By "full solve" you mean a completed load step right before the error, right? I have to clarify though that the error occurred when the solution couldn't converge on a few consecutive substeps... But generally (with different models of the same problem) the program just informs me that it will display unconverged solution so that I can see what went wrong therefore I am not entirely sure whether the crash was really caused by nonconvergence.
Thank you very much for your assistance so far. I will keep you updated.