usb stick problems

Since from first installation more months ago, my fedora 16 xfce have problems with files on usb sticks, especially with big files: often (90% of times), after I transfer files on it, won't umount (device is busy), and, once file are deleted (using shift + canc), space remain occupied; using delete as normal, a .Trash folder appear with file inside. For solve the situation I must use gparted, deleting and recreate the partition. Thanks for your help.