More than likely that's a common state when it takes a long time to update. Just leave it alone and give it all the time, it needs. Any interaction during the update may upset it so refrain from that thinking it really isn't doing anything, it is. Check you HD LED to see if blinks now and then for any activity, though it maybe slow as well.

Alas, you gave no clue to what your desktop consists of. If it has any special/unique features or extreme setting, then make sure you're at defaults or throttle down abit prior to the upgrade. If you have numerous USB devices attached, remove *only* have mouse and kybd. connected.

tada -----Willy Happy