I have a ACER notebook and this happens occasionaly. I am not sure what causes it but I think it could be due to holding down some key. What happens is that it brings up the alternative keyboard. On the ACER we get out of it by holding down a function key (it is an unnumbered one at the bottom of the keyboard next to the Windows key, and not any of the ones at the top of the keyboard)in conjunction with the Number Lock key. You may have to try something similar if you don't have the unnumbered function key.
My daughter called me from school and said her Sony Vios Laptop is giving her trouble. When she types letters on the keyboard it does not match the letter she is typing. She did a restart and the same results occured. Of course my first thought was she drop some liquid in/on the keyboard. She swears she didn't. She did a scandisk for errors and it took a 1/2 hour to complete with no results. She has Mcafee virus protection, Spybot and Adaware...all up to date. Any ideas?