Emails sent by webform contain "Array" instead of the actual data

Create a webform (mine contains fieldsets). Set it up so that it sends emails on submission, and include some data in the email. Simple text fields are incorrectly rendered in the email and appear as "Array", while other types of form element seem to work ok.

The usefulness of the email is seriously compromised by this.

In the example below, "Name of pupil" is a simple textfield.
"Instrument" is a select box (single option selection).

Sample email, showing "Array" where it should show data

Submitted on 14 Aug 2009 - 11:12
Submitted by user: admin

Submitted values are:

  Your details:
    Name of pupil: Array
    School attended: Array
    Date of birth: 17 January, 1997
    Home phone number: Array
    Mobile phone number: Array
    Correspondence address: Array
    Town/city: Array
    Postcode: Array
    Full name of parent/guardian: Array
  Instrumental lessons:
    Instrument: Euphonium
    Previous musical experience: Yes
    Preferred lesson option: C/D

The results of this submission may be viewed
at:http://mydomain.com/node/41/submission/344

I've searched for similar issues because I can't believe no one else has had this happen. Nothing shows up, but please point me in the right direction if I'm duplicating an issue here.