macbook air slow shutdown

My brand new macbook air 13" seems to have a pretty slow shutdown time (20s+).

As I am new to mac I spent several days trying to find a fix without any succes.

After a shutdown I just ran a console search for a exit timeout and found the following:

01/11/13 00:04:38,068 com.apple.launchd[1]: (com.apple.appkit.xpc.openAndSavePanelService[261]) Exit timeout elapsed (20 seconds). Killing

I think this might be the problem but I am not sure which terminal command should be used to reduce the killing time.

Could anyone please help me ?