I have two reports of the menu pages on the pdfs not rendering properly when you hit a “contents” button. This appears to be an Adobe reader problem – the application simply stops rendering the page. You can force it to render the page by rescaling or resizing the page. It may be simply to do with older machines. If it is a big issue then we could simplify these menu pages by taking out the triangle buttons and leaving only the textual links. There is, as ever with Adobe, no guarantee… but it might simplify the page enough to reduce some glitches…vote here for you solution.