Occasionally, Locator Spy is not able to expand the locator subtree. It only sees the top level window/object and the only solution I found is to reboot the PC (running XP Pro).
Closing SilkTest and/or closing the WPF application under test does not solve the issue.

Is there something that you know of to prevent this from happening?

Any other solution besides rebooting or restarting the system?