Sounds like a driver conflict. Been there once before. The old driver is still active or trying to be active. Some suggestions follow.
If your new keyboard is USB (most are nowadays):
1. Check in the system BIOS to see if you need to select whether to use USB or the PS/2 socket for the keyboard. Further check to see if you need to disable the PS/2 keyboard socket (some may BIOS require this).
2. Check in the system BIOS if the USB keyboard is to be controlled by BIOS or OS. Switch it to BIOS if it says OS. That way your BIOS controls it until the OS loads. You may need to do this step before you can completely uninstall previous drivers.
The above steps are typically in the USB functions or on-board device functions portion of the BIOS settings.
3. Try to plug the new keyboard into the same USB port you removed the old one from (hope you know). Sometimes Windows is finicky about this. It expects to find all the USB devices hooked up at the same ports when it loads the next time.
4. Try this last. I once had to delete all my USB devices from device manager to get WindowsXP to re-generate them and re-recognize my USB portable hard drive. (In the process, I discovered the plug it back into the same port trick noted above.) This is also an option for you as it makes Windows look for the device and regen the USB information for it. Of course, you have to delete one at a time and Windows doesn't tell you which device is which so you have to guess and note the addresses as you delete things and lose the operating ability. (USB Root hubs and controllers are paired up and deleting one deletes the adjunct.) One of those is your keyboard (and mouse if a combination) so you lose all input control once the one for the keyboard is deleted (and mouse if a combination). After deleting them, you reboot and let Windows re-discover them. Id din;t have to reload drivers, just let Windows rebuild its USB connection list.
Also, I expect you have checked to make sure you are loading the correct drivers for 64-bit Win7.
This link may help. Saitek Cyborg Keyboard setup?? - Other-Components - CPU-Components
The link raises a couple of good points. First, the driver may be buggy. Second, sometimes you have to load the drivers first, then plug in the hardware. You may want to re-check the installation instructions about this sequence.