[lebanon]

BBI-ross, well it could be because the yahoo actually writes a second file on ur system, and that will require writing permission, however (normally) since you are able to write on an open file, you should have been able to write on non-existant file.
Ill try to send you a modified yahoo file, where it writes on a temporary folder then u chmod that folder to 777, lets see if that resolve it, for now dont try to chmod ur whole directory it will comprimise your security.
As for gmail, the error is clear, your php.ini setting doesnt allow the function to work.