Dynamic chart axes shrink each time file is opened

I have a dynamic xy chart that has a shrinking plot area problem. Each time I save the file and reopen it (whether I added data to the plot or not), the y-axis moves a tiny bit, shrinking the plot area. I have XL07, but the file is saved as 97-03 for compatibility. I'm not using any macros. It's a simple report with two embedded charts. One uses the secondary y-axis, and this chart shrinks in from both sides. The other chart only shrinks from the primary y-axis. Under normal conditions, I have all worksheets and the workbook "Protected" with a password to prevent users from reformatting anything, but it didn't make any difference to the problem. Typically, once per hour the file will be opened, a line of data is appended to the "Data" worksheet, the file is saved and closed. I can reopen the file, make no changes to it, and if I save it on closing then the next time I open it, the axes will have moved in the plot area. I also do not understand why it asks me if I want to save on exiting if I've made no changes to the file. Thanks for any help.

Here is a blank report with some dummy data in it. I do have SP1.
Thanks.

Thanks for looking at this Andy. This happens to the two embedded charts on the 'Graphs and Shift Summary' worksheet. The "Gas Flow and Pressure" chart moves 0.11 inches in from both the left and right axes with 10 saves. This is on a WinXP Pro machine with screen set to 1280x800. The "Fluid Flow Rates" chart left axis moves the same distance but from left to right. I've attached an example of what this file would look like after about a hundred or two hundred saves.

I could probably do that (with some help on the code since I'm not good at writing vba, only modifying it), but I want to explore other options first to avoid requiring all customers to enable macros when they open their reports. I'll start by saving as Excel 07 (xlsx). If that doesn't work, I'll probably re-write the whole report from scratch. The original file came from many different people working on it before I got the file, so I don't know if it picked up some kind of bug before me.

Well here's what I've done...
Saving it in Excel 2007 as .xlsx fixed the problem. But formatting after file conversion into older versions of excel looked bad. I went back to the .xls version of the file and switched the view to Workbook View --> Normal instead of how I had always had the file with Workbook View --> Page Layout. This fixed the problem in the old format file. I guess this is a bug with saving the file in Page Layout view. I'm guessing Andy, when you opened the file, you were in Normal View? and that's why you didn't see the same problem. Thanks and cheers.
Matt

I am having the same problem of what I have deemed "incredibly shrinking graphs". same issue, the file was a .xls file, I changed to .xlsx and that seems to have stopped the problem. but what was interesting is that not all the graphs on the page exhibited the shrinking syndrom. Side bar comment: the 2007 graphing capability was great diminished. the loss of cross hatching, increases the use of ink, and reduces readability when in a black and white mode. what the heck were the developers thinking?