Hello everyone, I have installed on my macbook early 2008 Yosemite, but now I want to upgrade it to el capitan, how can I do ?? I have problems with macpostfactor because that tells me to go ahead with the installation I have to click on the ad, however, appears to me a pure white screen within the application .. Do you know how can I do? I have attached the photo of the problem with macpostfactor. Thanks in advance.