Rover project manager John Callas at the Jet Propulsion Laboratory in Pasadena said Monday that the rover is in a stable operations state called automode and can remain that way for some time while the problem is diagnosed.
The reboots occurred during the past weekend.
Callas says Spirit's batteries are charged, its solar arrays are producing energy and its temperatures are within allowable ranges.
The rover team is investigating whether the problem could be related to recent updates of the rover's onboard software.
Spirit and its twin, Opportunity, have been exploring the cold and dusty red planet since 2004