Preserving one's uniquely customized computing environment as one moves to different locations is an enduring challenge in mobile computing. We examine why this capability is valued so highly, and what makes it so difficult to achieve for personal computing applications. We describe a new mechanism called Internet Suspend/Resume (ISR) that overcomes many of the limitations of previous approaches to realizing this capability. ISR enables a hands-free approach to mobile computing that appears well suited to future pervasive computing environments in which commodity hardware may be widely deployed for transient use. We show that ISR can be implemented by layering virtual machine technology on distributed file system technology. We also report on measurements from a prototype that confirm that ISR is already usable today for some common usage scenarios. ? 2005 Elsevier B.V. All rights reserved.