How are these strange characters getting into Crystal Reports PDF Export?

We have a Crystal Reports 2008 report which merges database data with some SurveyMonkey free-text data stored in an Excel spreadsheet.

The free text data looks OK in Excel, looks OK whe开发者_如何转开发n copied/pasted to Notepad, and looks OK in the Crystal Report. But when we export the crystal report to PDF, a lot of strange box characters get appended to the end of some of the free text fields, like this:

When we inspect the data in Excel, there is nothing strange at the end of the text data. E.g. the cell that holds the data shown above ends with the words 'personal development' and then there is nothing else there.

Where are these characters coming from, why can't we see them in Excel, and how do we get rid of them?

Any help or suggestions greatly appreciated, because someone has to get this report to somewhere important by Monday morning, etc etc