How can remove redundant NET USE commands from the startup script

I am volunteering at a charity that has a small network on XP. When the PCs
start up they execute the cmd.exe and do redundant NET USE commands trying to
map to drives on a server that was removed some months ago. Is there a way
to edit the startup to remove these redundant statements. Which file is it,
where is it located and how can I safely edit it. Any help gratefully
received.