Please download the following and run the application "CLEANALL".
ftp://ftp.roland.co.uk/ProductSupport/DownloadsAndUpdates/Clean_All.zip
This will uninstall all Roland/Edirol/Boss drivers. Disconnected the UA-25 when prompted on screen and restart the computer. Run the driver installation for the UA-25 from the download I have placed below and reconnect the UA-25, this should solve it.
UA-25
http://www.rolandus.com/products/productdetails.aspx?ObjectId=704
UA-25EX
http://www.rolandus.com/products/productdetails.aspx?ObjectId=970