[support] Installing modules by the web interface.

Hello all. sense I have upgraded to the latest drupal I cannot get modules to install from the web interface. for example, I have clicked the modules link and clicked “install new modules.” When I do that I get the usual thing. ask for a URL or to browse for a module on your computer. I can do either one of these tasks and when I click install, it just takes me back to the same thing. When I do the steps above and click install again, it will take me to a blank screen. Does anyone know why this is causing this problem? Note: I have reinstalled drupal and ever sense, this has been happening. Thanks all.