Error Message

I received this message: Unable to open Assets/Free/House_Gameprops/House_02_1024.psd: Check external application preferences.
What does it mean? What should I do?

Try saving it as PNG instead of PSD

The message is in regards to external tools setting in preferences. Check out this link for information on how to set up the external tools preferences: http://docs.unity3d.com/Documentation/Manual/Preferences.html