I accidentally posted this on the other Sonar Forum instead of the X series.  I got a couple of good replies, especially one advising me to use the Windows Eject function instead of unplugging the USB drive.  I would be surprised if that made a difference for another device in another port, but I will test that.  Here is the original post:
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I have had an ongoing issue with USB keyboards failing to work with Sonar.  A PC reboot always fixes the problem (as far as I know).

Although I do not know the cause, I did discover that unplugging or plugging in a USB drive will cause the problem 100% of the time.

For example, M-Audio keyboard works fine.  I change Passport USB drives in another USB port.  The keyboard no longer works.  I reboot the PC and the keyboard works.

Any ideas why this is happening?  The good news is that at least I can relate the issue to a specific action, although there could be other causes not yet identified.
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I am not aware of that sort of issue - though I have a thought.
 
Is it possible you have left the default Windows behavior in place, when it comes to it dealing with USB Devices getting turned off?
 
There are multiple ways of getting to this to check/set it.  Here is one way - Hit your Windows button, then right-click on Computer and then click Manage.  This will open the Computer Management application.
 
Look on the left side, for Device Manager, and click on it, which will then open Device Manager.
 
Expand the Universal Serial Bus Controllers group, in the right side of the Windows, where the various devices are listed in tree-like fashion.
 
Once that is opened, you want to double-click on each Hub, to open its Properties dialog window.  Hub devices will have a tab at the top of their properties window labelled 'Power Management', and non-Hub entries will not have that tab.
 
So, for each Hub, click on the Power Management tab, then make sure you do NOT have a check in the box that says "Allow Windows to turn off this device to save power".  Click OK for any that you change and move to the next Hub.
 
This setting tells Windows to not be stingy with power, and turns off the Selective Disable functionality, thus leaving USB devices enabled.
 
Bob Bone

Bob, Thanks for this very thorough post which I am sure will be helpful to a lot of users.  I have checked the devices to make sure they don't go to sleep.  I have a Sweetwater Creation Station and it has a custom power plan.
 
The keyboard (or any keyboard plugged into the port) seems to work fine until I plug or unplug any other USB device.  Then I have to reboot the PC.
 
This is not specifically a Sonar problem.  The keyboard will not trigger stand-alone applications (like Ivory or Vienna) once it has gone off.
 
For the record, I have a number of USB ports in use: bluetooth for wireleass mouse/PC keyboard, MIDI keyboard, iLok, eLicenser, audio iterface, MIDI interface, passport USB storage.  And I may be forgetting one or two.

using eject flushes the buffer so it could be possible

+1
 
For a USB drive, you DO want to use the eject feature for sure, and the reason is exactly the write buffer. If you simply unplug a USB drive, Windows will not free that USB port in case there was a glitch to the drive and it can re-establish the connection. Windows will only release that USB connection if the drive is ejected or you reboot (if you have unplugged it without ejecting, you should also be able to plug it back in, eject the drive, and Windows will release that port for you).
 
This assumes you having this issue using the same USB port for the Passport and keyboard?
 
Michael

Could you have a power issue, where there are so many devices plugged in that they are eclipsing the ability to power them all properly?
 
Also, some USB ports are powered and some are not - wondering if that has any involvement with your situation.
 
If none of the above applies, sorry - this is kind of a quick drive-by post on my part.
 
Bob Bone
 

Hey, Bob.  Good thoughts.  One thing I could try would be to buy an externally powered USB hub.  It's not a great expense.

I was having trouble with my Casio PX-330, too. It would disconnect in the middle of playing a piece. I turned off power management for ALL the hubs as well as the ASMedia XHCI Controller (also under Universal Serial Bus controllers) and it so far, it's stopped disconnecting.
One conclusion I've come to is that if it happens again, I'm very seriously thinking of kicking USB MIDI to the curb and going back to a simple, old-fashioned MIDI set-up through my sound card.
 
One other tidbit I came across had to do with making sure to use external power supplies for all USB devices, especially the keyboard, but I can't imagine your M-Audio would work without it anyway.