Group Policy

I use group policy to set up the wallpaper for all clients (windows XP) It is running fine if I copy and keep the images in the all the clients (a lot of work because we have around 60 computers). Yet, if I have the image on the server and let it push through and on the clients, it does not work.

Do I have to enter the server’s name or any specific name for the clients to recognize?

Furthermore, when I change the wallpaper, the old wallpaper is still on the background. It takes about a minute or so for the new wallpaper to display. How do I fix it?

Any advice or answer is greatly appreciated.

Thanks