Storage drive prevents windows from loading

I have two HDD's one is an 80 gb seagate. I have vista installed on this one and use it as my main. The other is a 500 gb WD500AAKS that I have for backup and storage only, both are sata and both are about a year old. I noticed a few times the 500 gb not showing up in My Computer it would appear and disappear. Once it didn't even show up in bios. Ocassionally the computer would load windows so I ran a disk check on the 500gb and the check came back saying the drive was fine. Now if I unplug the 500gb windows boots fine, but if i plug the 500gb in I get stuck at the loading screen. The machine has also bsod'd 3 or 4 times in the last week with just the 80gb plugged in. Any ideas anyone might have would be greatly appreciated.Thank you