I spilled some milk all over my keyboard a month ago. It has slowly been improving (keyboard didn't used to work, but now it works near perfectly). The only problem that I still have is that the left shift button seems to be stuck.
It was mentioned above in this discussion that the c or esc button needs to be held down to not boot up in safe mode with a stuck shift key. This did not work for me. I held down the option key and that worked for me. Finally out of Safe Mode! I'm on version 10.7.5