Opening Excel 97 worksheet in Excel 2007 in compatibiity mode, I can hover
over an existing X-Y chart series and read the proper series name, time, and
value of that point.

But if I use my macros to delete all the data series, read in new data, and
then re-add the series (most settings on Auto), then when I hover over a
series and point, it more times than not gives the name of a different series
and a different time, and value! It can pick a series point that is over 1
inch away on the screen.

If I click on that point, it will display the same wrong series in the
formulas window under =SERIES(...).

I make sure that I did not have the wrong series pre-selected, just the
chart as a whole.

Naturally, the series that are added last (the ones "on top") tend to win.

Is there a way to reduce the gravitational pull of the series on top back to
Excel 97 levels?

I tried resizing the lines and markers to be thinner, but this did not help.