Word docs in "shareddocs" are defined as Read Only

I have an e-systems desktop and SWMBO has an ASUS netbook. Both are Win XP Sp3. The netbook is wifi connected to our home network and the desktop is ethernet wired to the internet.

We've got a few folders, most of which contain Word03 documents that we both want to work on (NOT simultaneously!) They are in "SharedDocs" on each machine and are accessible from either one.

The problem we're having is that when you're on one machine, trying to work on a Word document that's resident on the other computer, it always comes up as read-only - even if the other machine is idle or working on a completely different program. When you try to save your work, the machine requires you to "save as ", after which the home machine can't do anything with the revised document.

I can't find any guidance in MS Help. Any ideas, folks? I'm sure it's going to be one of those forehead slappers when I do find out how to do it, but right now I'm out of ideas.

As always, any help gratefully received.

BTW, I can't find anything in archive search or FAQ files to help with this one.