If Num Lock was in the OFF state on your G74SX, the LED to the right of the one that lights for Caps Lock would be OFF. Is that the case?
If not, I'd be tempted to uninstall the keyboard driver in Device Manager and REBOOT to allow Microsoft to install the Plug-n-Play keyboard driver.
There is also a registry edit (see
http://answers.microsoft.com/en-us/windows/forum/windows_7-hardware/windows-7-how-to-turn-off-numloc...) and a program called NumLocker that allows you to change Num Lock state. That would be what I would try if the Num Lock LED is OFF.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT