Hello,
my experience with USB sticks are that if you buy a new one and it has problems, immediately return it and do not use it. There were also a lot of fakes on the markets, which had a real size of only 512MB, but made Windows think successfully that the size was several GB. It also allowed Windows to copy data in that amount (built the Fat with the filenames, but all the data went into the toilet WITHOUT ANY ERROR MESSAGE WHILE COPYING).
There is one free utility specially for USB sticks which a big German Software magazine developed after they sent out a few hundred of those fake sticks to their users as gifts for subscribing to their magazine (and subsequently had to replace them all!).
I run this tool on all my USB sticks when first purchasing them. It bypasses the wear leveling and caching of the USB stick and allows you to test every single sector on the USB stick. I would recommend to format the stick as Fat/Fat32 for testing, and only after first testing format to NTFS if so desired.
The program itself can be switched from German to English when started, but the web site is German only.
Here is the link to the website translated by google:
http://translate.google.com/translate?prev=hp&hl=de&js=n&u=http%3A%2F%2Fwww.heise.de%2Fsoftware%2Fdownload%2Fh2testw%2F50539&sl=de&tl=en&history_state0=&swap=1
Here is the original German link:
http://www.heise.de/software/download/h2testw/50539
Here is the link for directly downloading the utility (which is a bit difficult to find):
http://www.heise.de/ct/Redaktion/bo/downloads/h2testw_1.4.zip
Definitely a must have in my tool kit.
Regards,
Pais