My first guess would be that the system was rebooted at the file modification time. Perhaps the disk was defragged. This file is used by XP's prefetch system to "index" applications and their files.

www.edbott.com/weblog/archives/000024.html

and it looks like by default windows updates that layout.ini file every three days. Look at the following link, under Disk Efficiency Optimizations
www.microsoft.com/whdc/system/sysperf/benchmark.mspx