What format is your USB drive in right now? FAT32 is the best format to use. This is the guide that I use and haven't had any problems (
http://www.wiihacks.com/showthread.php?t=96770). Just note that EaseUS is a great free program and like most free programs they try to install aware or other programs you don't need. Just read the installation screen closely and make sure you click no or decline to prompts asking you to install other programs.
When installing games to your USB drive, use a PC program called Wii Backup Manager (
http://www.wiibackupmanager.co.uk/home.html). This program will automatically split games that are larger than 4 gigs so they can be used on a FAT32 drive and work in USB Loader GX.
Hope this information helps. If you have any other questions let me know.