I
f you have some trouble with your Flash drive probably you have virus, almost all usb viruses are started with autorun.inf that sometime is problem to remove from your drive even if you format your drive, with this small tool you will easily remove autorun.inf and after that you can format your USb flash drive to be sure that you dont have any viruses, spy ware or other suspicious files 
Download: http://www.wikiupload.com/download_page.php?id=146586