Harddrive Shmarddrive

I've installed SATA hard drives before, but never had one of my own (my computer being the last thing to get fixed and/or upgraded). Things have been humming along with work and I'm thinking that I'll be able to get cauht up. But what's this? My computer decided to turn itself off and then not restart on Friday. After spending all day Saturday trying to figure out what was going on, it seem that my other hard drive has gone bad. Now considering my SATA hard drive is my master hard drive it should have started just fine. So, after unplugging my secondary hard drive I'm humming along just fine again. Weird...