New install problem

[Brian Galliford]

Dear Lilyponders,

I've been using Lilypond with no problems (and many thanks) for a couple 
of years on my old MacBookPro 17inch. 

I have just tried installing it from a clean download from your 
site on my new MacBookPro 15inch. 

On starting up the program however I get the following error message:

LilyPond Error
An unexpected error has occurred during execution
of the main script

ImportError: dlopen(/Applications/LilyPond.app/
Contents/Resources/lib/python2.6/lib-dynload/
objc/_objc.so, 2): Symbol not found:
_objc_sync_notify
  Referenced from: /Applications/LilyPond.app/
Contents/Resources/lib/python2.6/lib-dynload/
objc/_objc.so
  Expected in: /usr/lib/libobjc.A.dylib

+ 2 buttons at bottom of the window: Open Console / Terminate

I'd be hugely grateful for any assistance you could give. 

I have looked around the FAQs and other 
documentation to find a solution, but unsuccessfully. 

I apologize in advance if I've missed the answer and 
am grateful if you can point me in the right direction.

Yours gratefully
Brian Galliford