SlapOS is the first open source operating system for Distributed Cloud Computing. SlapOS is based on a grid computing daemon -called slapgrid -which is capable of installing any software on a PC and instantiate any number of processes of potentially infinite duration of any installed software. Slapgrid daemon receives requests from a central scheduler -the SlapOS Master -which collects back accounting information from each process. SlapOS Master follows an Enterprise Resource Planning (ERP) model to handle at the same time process allocation optimization and billing. Recent research on Cloud Computing has focused on the implementation of Service Level Agreements (SLA) and operation of large Data Centers. However, in case of Force Majeure such as natural disaster, strike, terrorism, unpreventable accident, etc., Service Level Agreements (SLA) no longer apply. Rather than centralizing Cloud Computing resources in large data centers, Distributed Cloud Computing resources are aggregated from a grid of standard PCs hosted in homes, offices and small data centers.