Had the same issue. Changed the file system from FAT to NTFS and it worked fine.
To convert FAT to NTFS, right click the drive name of pendrive -> select Format -> File system type select NTFS.
If NTFS is not available (only FAT is available), then Right click at pen drive -> Click Properties -> Select Hardware tab & click properties -> Goto Policies Tab -> Select Optimise for Performance. Now you should have NTFS in Format menu.
Hope this helps