XL97: Inserting Second Trendline into Chart Halts MS Excel

In Microsoft Excel 97, when you attempt to insert a trendline into a chart, you may receive the following error message: and Microsoft Excel 97 stops responding.

This problem may occur if all of the following conditions are true:

• The series in the chart contain a large (usually, more than 300) number of points. -and-
  
  
• The x-axis of the chart uses a time scale. -and-
  
  
• There is already a trendline in the chart. -and-
  
  
• The two trendlines (the one that's already there and the one you are trying to insert) contain a different number of points.

To prevent this problem from occurring, don't insert a second trendline into a chart whose series contain a large number of points, unless it will have the same number of points as the first trendline.

Microsoft has confirmed this to be a problem in Microsoft Excel 97 for Windows. This problem was corrected in Microsoft Excel 97 for Windows, Service Release 1.

In Microsoft Excel 97, when you create a chart, the x-axis of the chart may be formatted with a time scale. This will occur if the first column or row of data used to create the chart contains numbers formatted as dates.

When you insert a trendline into a chart, the trendline has a number of points. This number is determined by the type of the trendline. For example:

• Linear trendlines have two points.
• Moving average trendlines have the same number of points as the series to which they are attached.
• Other trendlines have a number of points that is proportional to the width of the plot area in pixels.

If the charts x-axis uses a time scale, if the series to which you are attaching trendlines has a large number of points, and if you insert two trendlines that contain a different number of points, Microsoft Excel 97 may stop responding.