Faulty 16GB Micro SD Card

hi just bought 16gb class 4 micro sd sandisk  card from amazon.

http://www.amazon.co.uk/gp/product/B001F7AJKI/ref=oh_details_o02_s00_i00?ie=UTF8&redirect=true

put into a cheap card reader  from amazon (which supposed to read up to 32gb) http://www.amazon.co.uk/MICRO-SD-MICRO-SDHC-MEMORY-READER/dp/B002WKD0CQ/ref=sr_1_7?s=computers&ie=UTF8&qid=1344328099&sr=1-7 

and connected to my usb2 port on my pc tower with xp sp3

some files copy, others crash/close the window with error/fail message  .   i re-open the  window and try again and sometimes it works , sometimes i repeat this process a few times until file copies over completely (and window does not crash or close).   but usually crashes again when trying to copy another file.  completely random. crashes on files as small as 10mb.

never crashes when reading the files.    have almost filled the card with fully working files trying to understand it and see if the capacity was there.  is is.    so i’m assuming it’s not a fake card as it is 15/16gb tested.

was 7 uk pounds so not overly bothered about returning unless fully sure card is faulty.    at themoment not sure if it is reader or card.