Took to Genius Bar but since it was not doing it at the time they said to just document it when it happened again.
When the issue occurs, do you have any peripherals connected to your computer?
Mac OS X (10.4.6)
Use Software Update to update your os to 10.4.11 and anything else that needs to be updated. Afterwards, repair permissions and restart your computer. If the issue returnes with no peripherals attached to your computer, take the computer right back the repair shop.