Handbook glitch: not nice.

In MathCad 13/Windows XP Pro, when I open the Signal Processing Hbk and go to the page "Quantizing a Signal," everything is OK until I page down a couple of pages. Then MathCad tries to access something it can't find and it puts up two information boxes repeatedly. I can't get out without closing the boxes, but as soon as I close it a new one keeps opening. This ends in the 3-finger, Task Manager, close Mathcad, then reboot for good measure. I'd look now to report exactly what the dialog box says, but I'm afraid I'll lose this message.

I've seen this in other places in the Handbooks, but this is a definite reproducible example.

Any ideas?

Stan