In fact, when a serious problem is detected by the craft's own protective software, it sometimes uses a reboot, plus the subsequent automatic sequence of steps that that triggers, to correct the problem or, at least, to keep itself safe until human experts can intervene. But now it is an extremely complex and difficult process, as the operations team has to help the spacecraft use its camera to lock on to a reference star. The principles underlying this remarkable trick to allow the spacecraft to orient itself in outer space without the equipment that was designed for this purpose were described extensively in mission logs from March through August 2000. This aims the antenna close enough to our planet to allow reliable communications. By knowing that the antenna is pointed approximately at Earth, we can calculate roughly where the camera is pointed.
Engineers instruct the camera to take some long exposures and radio the resulting pictures to Earth.
Then analyzing the locations and brightness of the few faint stars in those images allows a determination of exactly where the camera is pointed and thus the precise orientation of the entire spacecraft. The details on the exact pointing are sent back up to the craft along with directions to a preselected lock star. While this procedure is taking place, the craft relies on directives from Earth to maintain its orientation. In fact, their instabilities induce a tiny drift in the craft. This very gradual motion is more than 10 times slower than the hour hand on a clock, but in this exacting work, that's too fast to be ignored.