I have a strange and very annoying problem in firefox 33, this problem was there in firefox 32 aswell but has become worse in firefox 33. When my browser has been open for some time, tab scroll button appears on the right hand side of the tabs bar along with a small green '+' button to open a new tab further to the right. This is rather than the normal new tab button that is supposed to be next to the right-most tab. Now I know that this is supposed to happen if I have too many tabs open but this is happening randomly even when I have only a few tabs , sometimes only one!! When these buttons appear I can solve the problem in two ways, either open several new tabs and then close them , this gets rid of these buttons or close firefox and start again. I have the following add-ons, classic theme restorer, classic toolbar buttons, and keyword search. And also adblock plus. I've had these add-ons for a long time and didnot have a problem in uptill firefox 31.