Operating system: "Windows 7"
(The About GPA dialog gives me the following data:
"GPA version 0.9.4 ...; GnuPG 2.0.22)

steps to reproduce the bug

1. open GPA

1.1. Switch to 'Detailed" view

1.2. Select a key so that its details are seen at the bottom of the form.

2. press 'Preferences" button

3. click the tickmark box "Use advanced mode"

4. now the tickmark box "Use advanced mode" should show the tickmark

5. click the tickmark box "Use advanced mode" AGAIN to clear it

6. Windows message appears "gpa.exe has stopped working"

7. Program is being closed by Windows 7.

That's it.