I suggest to disable the sleep (S3 suspend) timer by default in KDE for the LiveGUI USB image. While I was emerging packages, the laptop unexpectedly went to sleep as triggered by the timer, interrupting the emerge process. Worse is that S3 has never worked right on some laptops, on mine it just locked up and I had to do a hard reset.
*** This bug has been marked as a duplicate of bug 925002 ***