Node author is changed when admin edits

Hi
I have created two content types ('personal info' and 'profile info') to form a user profile and it worked well.
So the flow was like this : when a user updates his personal info, a row is inserted in {node} table with content type 'personal_info'. There is a table named {content_type_personal_info}. All the information is stored in that table.
Now when a row is inserted in {node} the uid field is filled with that user who updates his personal info. So when I am pulling data for that user I am checking in {node} table where type is 'personal_info' and uid is the user id of that user. Things running ok upto this point.

Now when admin updates the user's personal info the uid field in {node} table changed to '0' instead of that user's id. So I cannot pull data with the same logic as before. Even if there is no way to get the user's data.

I don't know if any body faced the problem like this, or I am missing something.