External Hard drive

I purchased a box for my 30 gig hard drive from my old DELL and Barracud 7200.7 and when I connect everything, it recognizes it but then tells me there must be something wrong.The message says there may be a problem with the hardware. However it worked great until now. The directions told me to make sure it wa switched into Master mode? Also there were no directions for windows XP. Anyone got advice(other than telling me I need to go to school)