I don't have permission ( and it's driving me crazy)

This has been bugging me for moths but I finally got bored of it and thought about sorting it out.

I have a Mac pro tower running lion and a MBP running running 10.5.8

I transfer files between then via a wireless net work all the time. But when I open one I can't save it again as it's locked and I have to do a "get info" and put in my password in order to continue. I never had the problem when both machines where running Snow Leopold.

I have the same account / user name on both machines and I have the same password. I've been into the system prefs and made sure that the sharing / users are set for read-write.

Can some one please tell me how to set the machines up so I can just pass files between them as I used to in Snow Leopold.

Thanks in advance