[xubuntu] problem with graphics after installation

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http://ubuntuforums.org – i installed newest ubuntu relaese yesteday and everything was fine till today. when i turned it on there was this message: the system is running in low-graphics mode. your screen, graphic card and input device settings could not be detected correctly. you will need to confugure these youself. [ ok ] if i press enter (mouse doesnt work) i get next message: what would you like to do? O run in low-graphics mode for just one session O reconf (Hardware)