I am a first-time Linux user who has installed Ubuntu 12.04 on a Dell Dimension E510 that used to run Windows XP. I cannot get Dash Home to open. The other apps open: Firefox, Libre Office, etc., but when I click Dash Home the screen flickers a couple of times and no dash opens. No window with search bar and whatever else is supposed to be there. I have tried several of the suggestions in this forum, but nothing has helped. I have also reinstalled Ubuntu from the boot disk, but Dash still will not open. Does anyone have a solution that can be communicated clearly? I will not understand much Linux terminology.