Our society is faced with an increasing dependence on computing systems, not only in high tech consumer applications but also in areas (e.g., air and railway traffic control, nuclear plant control, aircraft and car control) where a failure can be critical for the safety of human beings. Unfortunately, it is accepted that large digital systems cannot be fault-free. Some faults may be attributed to inaccuracy during the development, while others can come from external causes such as environmental stress. Radiations, electromagnetic interference and power glitches are some of the most common...