The page file is an area of your hard disk that Windows uses as extra memory space to store files and data that are currently being used. Of course, since Hard drives are magnetic storage devices, and not dynamic like RAM, the data stored in the page file stays there until it is cleared or over-written.
This data may possibly contain unencrypted passwords or other sensitive information since many third party programs do not bother to encrypt data that is being passed to the memory, even though it may end up on the page file. A simple registry change can force Windows XP to clear the page file each time it shuts down. Note that enabling this will increase the time it takes your system to shutdown.
Procedure to follow
Click on Start—>Run type regedit click ok
Navigate the following key from left pane
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
From the right pane double click on ClearPageFileAtShutdown key change the Value from 0 to 1