Problems with NX6 advance simulatio module

[Mendiriv]

Hi

I am mechanical engineer and I don´t have much experience with nx.
I have installed NX6 on my machine but the advanced simulation module doesn´t work. When nastran job is finished it says that the result file is empity.
I read a solution on this forum where I have to change the directory of Scrath. I´ve tried to setup to C:\temp but i cannot change the directory. The system sends a message that says You don´t have acces to the user default

Haw can I ghange the directory? and How can I get acces to the user defaults file

Thanks a lot in advance