right click My computer> Properties> Hardware>Device manager, right click the USB drive (Disk drive section), double click go to Policies tab, and select the Optimize for performance. OK.
(use the safety remove icon from taskbar, from now)
Or you could just format it different.If you saved the files U have on it first! (right click drive letter in My computer>Format)
Maybe NTFS. And U can even copy files bigger then 4 gb on it.