Shared File - Compatability Issue

We run excel 2007 on four PC's in the department and all regularly access a large shared file. Two of us are running windows 7 and two are running windows XP. One of the XP users keeps getting kicked out of the shared file, but only when a windows 7 user saves the file. When she gets kicked out of the shared file we find that there are a number of 'users' in the file that aren't actually in it, for example it will think I'm in it three times. The file type is a excel 2007 file type, i.e. XLSX. She isn't losing work per se as she is able to save as something else and then copy/paste into the shared file once she's back in it, but it basically means the file is no longer shared which is time consuming.

I looked through the forum and couldn't see anything quite like this, but apologies if I've missed something or posted in the wrong forum.

You get all sorts of problems with shared files, you'll find that the general opinion of them is that they're the spawn of the devil They corrupt often and give you all sorts of random headaches.

Ideally they should be avoided like the plague, there are lots of better solutions out there, access, google docs etc.. that offer much more robustness

Try making a copy of the file and use that, if you absolutely must used shared workbooks, keep them extremely simple, just tables of data and back them up regularly