Why cant I switch from lowercase to caps without having to click my mouse?

this happens in all applications; Word and internet etc. when im typing a sentence or even a word if i want to type a capital letter at the front of the word i press the caps lock key but then when i press the caps lock key again to turn it off and type in lower case the keyboard seems to disable. I then have to click the mouse back on the word before i can continue to write. very frustrating that i cant just type a sentence normally without having to click my mouse several times. can anyone help?????? ps this is why im writing in all lowercase =)