When we use technology to teach mathematics, we hope to focus on the mathematics, restricting the computer software systems to providing support for our pedagogy. It is a matter of common experience, however, that students can become distracted or frustrated by the quirks of the particular software system being used. Here, experience using the systems Maple and Matlab in the classroom is described with a view to highlighting the places where students are most likely to experience frustration. Strategies to help them avoid the common pitfalls are given.