Word 97 & Windows XP: Prob opening files

I’ve recently installed XP Home Edition with SP1 and up the various updates from the Microsoft site. I then installed my trusty copy of Office 97 and am having a problem when I open Word for the first time. The application seems to run OK but when Itry to open a file, I get a pop up window saying “.doc is being used by Scott Rasmusen (i.e. my own name) Do you want to make a copy?” If I cancel this everything seems to work fine – if I open a further file in the same session the pop updoesn’t appear. Does anyone know what is going on? It’s more of an irritation than anything, but it has certainly spoiled my enjoyment of XP so far.