I don't know if this will help, I found it few weeks ago:
File and Folder Ownership
Again, here is an item which I experienced, but you might not. In case you do, though, you'll have a fix at hand. For reasons that had more to do with a broken NetInfo database than anything else, Jaguar didn't recognize me as me. I might as well have been somebody else, and to Jaguar I was. The solution was to take ownership of my original Home folder and its tree. There are two ways. The Mac way is to press Cmd-I while Home is highlighted in a Finder window, and make yourself the owner of this folder and all of its contents. The unix way is to pop a Terminal window and type the following:
% man chown Check manual before starting (spacebar through)
% pwd Verify present working directory
% cd .. Move up one level above Home folder
% ls List contents
% sudo chown -R damien damien Take ownership of Home tree
% cd / Move into root folder
% sudo chown -R damien Applications Take ownership of Applications
% exit
Now, it's obvious enough why you should take ownership of your own stuff, but why Applications? Because you want to be able to add and remove items from it. Now the test is whether or not you are free to do this now. If you are, then leave it alone. But if it's a problem, you will know what to do.
If things get really nasty, you may have to set file permissions also. I don't recommend this lightly, because certain files and folders have tighter security than others for a reason. But if you have to, here is how to set permissions on all of the files in your Home folder:
% man chmod Check manual before starting (spacebar through)
% pwd Verify present working directory
% cd .. Move up one level above Home folder
% ls List contents
% sudo chmod -R 640 damien Set permissions in Home tree
% cd / Move into root folder
% sudo chmod -R 755 Applications Set permissions in Applications
% exit
If you absolutely have to set permissions on your Home folder, then also set tighter permissions on private files and folders. The code 740 makes a file usable by you, readable by other group members, and off-limits to anybody else. The code 600 sets it to read/write by you alone. The -R switch sets the recursive bit, so that all contained files and folders also get set. If you happen to use public and private keys, I recommend you create new key pairs after monkeying with permissions in Home. In general, this is very tricky stuff. Don't leave the door open, but don't lock yourself out either. Which brings us to a related topic.