Do you have Daemon Tools installed? An HP document for their OpenView product on page 13 of 18 says that Daemon Tools will use that .sys file and lock it exclusively, causing the backup to fail. You can read it here:
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01120421/c01120421.pdf on page 13.
Hope that helps!