Description of problem:
When the preferences are changed, they can not be saved. After "OK"
button is clicked, an error message pops up with "Failed to save the
preferences file. Any preference changes will be lost at the end of
this session."

Version-Release number of selected component (if applicable):
1.0PR

How reproducible:
As in description. Every time.

Steps to Reproduce:
1. open preferences window
2. change some options
3. click "OK"
  
Actual results:
Error window: "Failed to save the preferences file. Any preference
changes will be lost at the end of this session."

Expected results:
changes are saved successfully.

Additional info: