Hi,
in the latest release (0.2.2) all is fine when not upgrading with 'pacman -Syu', all runs smooth.
if i upgrade with pacman minepeon runs for ~10 minutes and then it doesn't respond anymore.
i use 10 block erupters with my Raspberry Pi Mod. B Rev 2.0 512 MB RAM
all is fine if you don't upgrade

Do you reboot after the upgrade? I just want to be sure that everything was sync'ed to the disk.