Can't Put in My Password to my MAC

Can't Put in My Password to my MAC

If my MAC has reverted to the login screen for the machine, and I try to enter my password, it doesn't recognize the number keys except intermittently. I can type in letters, but not numbers. Makes it very hard to get in if it goes to this state. After a while, it finally does, sometimes. Other times, it never does and I can't get into my own machine.
I'm running MAC OS X Lion, and the phone is a Motorola Droid.