Admin problem for Advanced Poll

I have been using for a while and it has worked perfect. All of a sudden I can log into admin area and see main page there. Howebver when I try to do anything it takes me to the log in page. I log back in but it takes me back to main page and if I try to do anything it just repeats back to log in.

I have tried changing password off my MySql manager and still no difference I think it might be something with cookies but not sure. ANy ideas or help is apreciated.

Try updating by replacing all files except the config file.

I confirm. U helped me. Thanks a lot.