[Camino] insufficient privileges to update to camino 1.5.5

Hi everyone
New to the list :)

Can anyone tell me why I can not move Camino 1.5.5 from the 
installation window over to Applications? I am an 'administrator' on 
our eMac, so usually no issue with updating software. We are running 
1.0.4 on OS X 10.3.9, prompted to download the new version when 
visiting the Camino page (looking for answers to another question - so 
haven't even got to that yet!).

The first message that pops up tells me there is an existing/older 
version, do I want to replace it? Yes.
Then the next one says I have insufficient privileges and cannot 
complete the operation.

I had quit Camino in both my user and the other user's account, not 
running at all when I tried to install the new version.

Any ideas?

cheers
R.