Matplotlib temporary files

Hi

have a Python application using matplotlib installed on a windows machine using PY2EXE. Am having some problems because the application appears to be writing some temporary files to C:\ but users do not have permission to write to this directory. It looks like matplotlib is writing the temporary files - can I supress these files? If not, how do I "tell" matplotlib to write somewhere else (eg C:\windows\temp)? Thanks in advance

Alun Griffiths