I have Illustrator CS 2 Tryout installed on my PC on Windows XP. I have installed Scriptographer 2.0.022. My script contains exactly one line:
activeDocument.getSelectedItems()[1].tabletData = activeDocument.getSelectedItems()[0].tabletData;
I draw 2 lines with the brush tool with my stylus (trying to make them look very different in width variation, so I can witness changes) and selct them both. I then select my script in the Scriptographer window and hit the play button. Sometimes one of the two selected lines receives a constant width (not the tabletData of the other line) - drawing another line with the brush tool then causes Illustrator to freeze. Other times Illustrator freezes immediately without changing one of the lines.
I thought this might be due to the tryout version, but I had the same problem on my computer at work.
The same problem occurs with more complex code like taper.js from Hiroyuki (see http://www.scriptographer.com/Forum/Wish+List/Control-Calligraphic-Thickness/).
If this problem does not occur on other computers (like yours, perhaps), it might be the different versions of Java Runtime Environment we have installed? Just a guess.
Yes, learning how to create my own plugins by going through Adobe SDK is currently blowing my mind, but it's a lot of fun too :D