This can be a calibration problem of your touchscreen. Does the top part of the touchscreen behave normally otherwise (can you reach Close and Minimize buttons)? Or does Firefox not respond to clicking, either? Give us a description of how you tried to "touch" the tabs in Firefox, what were you trying to do (switch tabs, I suppose?) and what happened when you did. What platform do you use? On most, you can use Ctrl+Tab, Ctrl+Shift+Tab or Ctrl+Num1 through Ctrl+Num9 to cycle through tabs.