Hi ohmghimire,
Thanks for visiting Apple Support Communities.
If you're seeing unexpected behavior when using USB devices, try resetting the SMC on your MacBook Pro:
Resetting the SMC on portables with a battery you should not remove on your own
Note: Portable computers that have a battery you should not remove on your own include MacBook Pro (Early 2009) and later, all models of MacBook Air, and MacBook (Late 2009).
- Shut down the computer.
- Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
- On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
- Release all the keys and the power button at the same time.
- Press the power button to turn on the computer.
Note: The LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC.
You can find the article with these steps here:
Intel-based Macs: Resetting the System Management Controller (SMC)
http://support.apple.com/kb/HT3964
If you still see this behavior after resetting the SMC, or your computer won't turn on, try the steps in this article next:
Troubleshooting: My computer won't turn on
http://support.apple.com/kb/ts1367
Best Regards,
Jeremy