You can technically remove the U3 software from the USB drive. But you removed it properly right? To remove the U3 technology from the drive, you have to go to the U3 Launchpad and, under Settings, select U3 Launchpad settings and click Uninstall. This will completely remove the U3 Launchpad from the drive. Don't just delete it.
Try restoring the U3 again. There is a U3 Launchpad Installer utility that you can use to re-install the U3 Launchpad for your drive.
Try that to see if it helps...