i actually may have found the problem. i was running 3 2tb hard drives, a 1 terabyte hard drive and a 3 terabyte hard drive, and they were all plugged into the back of my pc. i split it up a bit and plugged some of them into the front and some of them into the back so as to split up the load, and i haven't had a problem yet. i'm going to see how it goes for a while before i mark it solved though.
i know for sure it isn't the filesystems. i just went through a 2 week long process of slow formatting all of them.
plus all the drives stop working at the same time, which makes me think it was just the the usb getting overloaded.