fail in the system - urgent

hello, i tried to plugin some extension to the community builder, but first from the extension-install (of joomla), it didnt worked so i tried with the CB plugin management and it worked. but after i done this i get fail massage all over the site - white window with "Direct Access to this location is not allowed". i get it when i try to login to my user on the front page, i get it when i try to open "user management" from CB menu. i cant work with it right now. what can i do?

What plugin specifically did you install? It sounds as if you installed a J1.0 legacy plugin into J1.5, which would require enabling Joomlas system Legacy plugin. This happens when a plugin does not utilize CB API and uses Joomlas.

plug_cbmystocks_Ver_1.2 , what do i need to do?

Please navigate to Plugin Manager within Joomla (NOT CB Plugin Management). Once there locate the Legacy system plugin and enable it. This should resolve the legacy issues. I recommend contacting the developer for them remove Joomla specific API and use CB API removing CMS dependency.

i done this and it solve the problem but now i have the same problem - to open a new field, in cb field management, it show me the same white window and "Direct Access to this location is not allowed". why i get these white windows?

You get those errors because the 3rd party plugins being used are not coded for the CMS you're using. They're likely coded for Joomla 1.0 and you're attempting to use in 1.5 or 1.6. Please uninstall the plugin.