Outlook Message when trying to store message in personal folders

[Stacy H.]

When I attempt to store many of my received messages in my Personal Folders, I get the Microsoft Outlook message: "The item could not be saved because it has been changed by another user or in another window. Do you want to make a copy in the default folder for the item? Yes No " Why am I getting this message? My computer was recently updated at work and loaded with Windows 2000 5.0 Professional, service Pack 3, and has Microsoft Office XP Professional and Microsort Outlook 2002 SP-2.