Ciao Claudio,
I am pretty sure you ran out of memory.
Here are some things to consider:
What is the size of your input data?
How much RAM do you have on your computer?
In a separate window, you can run the following command:
top
then press M (upper case) to sort by memory usage. That will show you how much memory each process is using. Once you familiarize yourself with the information displayed by top, run your command in the other shell and watch its memory usage.
cheers,
-z