I plotted some contour plots using Origin 6.? demo versions. I wasted a few days to study some features on the graph, only to find out that it was created ARTIFICIALLY by Origin. I'm really angry with this.
A check using an older version (5.0) of the program produced the RIGHT plot.
I enclosed the worksheet data for you guys to verify. The address is http://people.physics.tamu.edu/xil/con1.dat. I used EDIT:CONVERT TO MATRIX:REGULAR XYZ to generate the matrix. Note the islands on the contour plot. They are not supposed to be there. It should be some line features from left to right.
I downloaded your data and created a contour plot from the data. In version 6.1, a reminder message opened before the plot was created letting me know that "To speed up your work this graph will be displayed in 'speed mode'. Therefore, some data may not be visible. To turn off speed mode select Format:Layer from the menu and select the Size/Speed tab."
This Reminder message may not have been there for Origin 6.0. I am sorry that you spent so much time studying the graph with the speed mode setting enabled.