My problem seems to be slightly differnt from the majority of USB probs posted. In my case I have an iaxe393 usb guitar, it is installed and working under a windows XP pro pc and works fine. When I first tried to install it on my Sont vaio PCG GRX 316 MP under win xp pro it was giving me device not recognised errors typically error 43 which I was never able to resolve. Now it's upt the anti and cannot see it at all, I have tried all inputs and it will not apppear in the device manager list of usb serial bus controllers so there is no error message to mention I have downloaded a program called USB view and swapping devices around I can see what ports are available and the number etc so I know the ports work. I have tried many defferent usb leads just in case they are faulty to no avail. The Support people at Behringer have told me to make sure I have the correct driver, well I have it's just I have never had the opportunity to install it. Beyond that they are effectively saying that the 3 laptops in my household are all defective. What is supposed to happen is that windows should recognise the device install a driver then you just up date it, i have only managed to do this on the original PC, so it's a bit of achocolate tea pot at the moment because I have no flexability toi use it other that at home!. I have tried unistalling all the usb host controllers and hubs I have tried witching it off and on again (thanks "The IT Crowd" a program I actually like alot!) I have tried taking the battery out ..standing on my head and doing a rain dance, all that happened is neck ache and it rained. I have tried a fix mentione in KB976972 this was saying something about chipset probs which i don't think I have not that I could find out exactly what chipset I have anyway I have tried installin it on my Inspiron 1545 windows 7 lap top I have tried installing it on an Inspiron 1520 windows vista laptop Anyone who has any clue what on earth is going on is very welcome to suggest something as I have reached a total impasse. I have had a go at looking under the windows registry usbstor etc but I cannot work out what if any are erroneous entries.

Sounds like a driver issue from the manufacturer to me. Try uninstalling the driver, then reinstall and see if it will detect. Make sure you have the latest drivers and insure you get the appropriate driver package (32 vs 64 bit). If there is no uninstall feature for the driver, or it fails to clean out all traces of the driver and your item still is not detected then I suggest you use system restore to restore to a point prior to the first detection and installation attempt. Failed USB driver installations can cause a device to not be recognized properly, especialy if the manufacturer did not provide a decent uninstall utility.