About an hour and a half after going to bed, the STS-135 crew of Atlantis was awakened at 6:07 p.m. EDT when one of the five General Purpose Computers used to operate the shuttle dropped off the on-board network. GPC-4 was being used as the systems management computer for Atlantis. The crew worked a standard malfunction procedure to swap system management from GPC-4 to GPC-2, completing the procedure at 6:47 p.m. Atlantis is in a stable condition with no concerns for the crew’s safety. Mission Control offered, and the crew accepted, an additional 30 minutes of sleep, which means the crew now will awaken at 12:59 a.m. EDT Friday. Troubleshooting will be performed after the crew wakes.