I'd replace the Midiman USB UNO but have not found another unit that is known to be compatible with Windows XP Media Center edition. I believe the problem is with the interface. Someone suggested I download MIDI-OX to test my set-up & I did so, but input from the XP-50 is not being detected. It worked for about a day & then stopped. Sonar successfully outputs to the XP-50 & another MIDI device, a Roland XV-5050, but won't consistently accept input from the XP-50. Most makers of USB-to-MIDI interfaces disclaim compatibility with this particular OS, although it is essentially XP Professional with some special features. I'm using Windows XP Media Center Edition (Service Pack 3). My input device is an old synth - a Roland XP-50 - but always interfaced pretty well with the computer until the latest fiasco. It has taken multiple attempts to hook up my gear, load drivers that didn't work, uninstall drivers, re-install drivers, etc. Specifically, I am using Sonar 8.5 & have two external MIDI devices that are driven by Sonar, one of which should also serve as an input device. Since then my set-up has been precarious at best. I used a Midiman USB UNO 1 X 1 with my system for years with no problem but recently had a computer crash & had the hard drive re-formatted. Windows XP Media Center Edition - Need Compatible USB-to-MIDI Interface

Usb uno midi interface driver