Julie,
Yes that is what I did

.
I fixed it all by unsharing the resource pool on all of my sub-projects. I then created a new resource pool and and linked the sub-projects to it. Finally I created a new master project and brought in each sub project. This time did not share the resource pool with the master project. I did all this in the folder on our server.
Glad to say all looks OK now.
Many thanks
Tony