When you shutdown your Windows XP computer, it may take more time to complete the shutdown process. Slow shutdowns are caused by a number of factors. One of the common cause is the Clear Pagefile at Shutdown option enabled.
Virtual memory support uses a system pagefile to swap pages of memory to disk when they are not used. On a running system, this pagefile is opened exclusively by the operating system, and it is well protected. However, systems that are configured to allow booting to other operating systems might have to make sure that the system pagefile is wiped clean when this system shuts down. This ensures that sensitive information from process memory that might go into the pagefile is not available to an unauthorized user who manages to directly access the pagefile.
When this option is enabled, it causes the system pagefile to be cleared upon clean shutdown. This takes considerable time of the Operating System to flush-out the pagefile, thus causing the slow shutdown. You may disable ClearPageFileAtShutdown option to improve shutdown times. But the pagefile.sys will be intact and accessible via other Operating System, in case or dual or multi-boot.
Some points to improve the shutdown times
Start Registry Editor and navigate to the following key:
[HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management]
Set ClearPageFileAtShutdown value to 0
Or, using Group Policy Editor [for Windows XP Professional]
Click Start, Run and type Secpol.msc
Click Local Policies | Security Options
In the right-pane, set Shutdown: Clear virtual memory pagefile to Disabled
