Network applications slower than molasses

My company has a s/w product that is installed on a
server and accessed across a network via a shortcut to
the executable on the server. With XP Pro our program
has now moved to a CRAWL on the workstations. One of our
customers has a network guy come in, and he changed the
way the OS loads our program, and it now runs quick as
can be.

My problem is that he didn't tell my customer EXACTLY
what he did, and I am unable to reach him directly. I
have several other customers who have the same problem
and I would like to be able to help them.

Anyone know how to change the way the OS loads programs??

Thanks!
..