Got a teacher who asked me to look at a problem with his work Vista notebook.

When logged onto the network he has full access to his files. However, recently he took the notebook to make a presentation to a local organisation and although it allowed him to boot up OK it would not allow him to access and display the work (which was on a memory stick) he was trying to present - in the end he did the presentation with his memory stick on one of the external organisations PCs.

What could be the problem?

The machine is one that I hadn't been aware of on my weekly visits before and it was badly in need of an update and had no AV on!