No you can't. The whole purpose of using MS Project 2003 Professional with
MS Project Server is for the user of MS Project 2003 Professional to make
changes to the project plan.
One way companies have "solved" project mangers from forever tinkering with
a project is to use a "Project Coordinator". How this works is that the
Project Manager hands over the project to the "Project Coordinator". Day in
and day out, all the Project Coordinator does is accept time and re-publish
the project. Any changes from the PM has to be approved by the project team,
not just the PM.
Of course, this creates another boat load of problems but at least your
project won't change...
Will it work for your company? That' I don't know...