Are you sure that USB is enabled on your computer? If so try a different USB port.

Are you sure that the USB cable is working?

My Keystation 49e just showed up (XP) without installing any drivers.

I've tried swapping cables and ports, its the same result every time

thank you all for your suggestions by the way, I hate to bug everyone for help as I usually enjoy working these things out for myself
 
I just dont understand midi that well to begin with but I'm learning I guess :)

The thought of having all these new sounds at my fingertips is too much to ignore!

according to your manual:
If you are using Windows XP or Mac OSX, you can now simply switch the keyboard’s power switch to the “ON” position. Because the Keystation 49e keyboard is class compliant, it will work without any further installation.

Just to be clear, that means that the drivers are built in to the keyboard and are loaded into Windows versions later than 2000, when you plug it in. If you installed drivers (as opposed to some other software that came with it), they are drivers for Win 98 or Win 2k and may be hijacking the device.

Uninstall them.
m-audio.com/index.php?do=support.faq&ID=187473ccf8b0d9096d3774e7e46d0733

Your keystation will probably show up under that name in device manager when properly installed.
To test that it is working and not a problem with Sonar :
m-audio.com/index.php?do=support.faq&ID=1d45c0102bde3d9bffb19c0056d9b171

Incidentally, there seems to be a problem with getting to these links by clicking directly in the forum. The long link is truncated by the forum and you will need to copy the full link without a space or line break into your browser address bar to get there. You may have to append http://www. before the link text above.

This may also be relevant. It is written for XP but probably also applicable to Vista:
m-audio.com/?do=support.faq&ID=d09d277334439e5ece97358dd62148fd

hey thanks for the suggestions, i tried uninstalling the drivers but there was no result
 
it doesnt show up in device manager or the MIDI-OX software.. windows just doesnt seem to know its there at all no matter what I do!
 
I think I'm close to exhausting most of the issues here, no idea what to do next :/

I also just tried plugging the keystation into my laptop just now but it doesnt recognise it either..

Seems you probably have a defective keyboard. Where'd you purchase it from?

Does the blue light come on when you switch the Keystation on?

I bought it from dv247.com and yep the blue lights come on

It matters where you get power to run it. If you are getting it from the USB port you may need to goto the properties of that port in device manger and be sure the power is always on. Ideally use a wall wart to power it and save the power drain from your PC. XP or Vista should alert you when you power it on if it is installed correctly.