ok, i'd do a full back-up right away, because if one of your drives fails, you will loose everything. Then download this:
http://www.seagate.com/ww/v/index.jsp?locale=en-US&name=seatools-win&vgnextoid=552bd20cacdec010VgnVCM100000dd04090aRCRD
you can use this tool to check your drives.
Let...