Computer randomly locks up when firewire drives are connected?

Question

Here's what I have:
- 2011 27" iMac i7
- 2011 15" MacBook Pro i7
I recently replaced all of my USB hard drives with Firewire drives, mostly as a speed and simplification measure. Under USB, I had to have a series of hubs which seemed to slow things down pretty dramatically, as well as cause a lot of weird behavior, like randomly ejecting. And, of course, there was the inevitable birds nest of wires. So, since there was no way to add USB ports to the iMac, except for hubs, I decided to move FireWire and daisy chain them.
This was all connected to a dedicated iMac workstation, the MacBook was never connected to the drives.
The drives were added a few days before a complete system overhaul was done. The system had been acting funny. We're little things here and there (finder often had to be relaunched after a restart, wifi was not able to automatically connect, etc.), and the system was starting to lock up on a somewhat regular basis. So, Lion was installed fresh and nothing was restored from Time Machine except for a few applications here and there (nothing system related). Once the system was all freshly installed, the little quirks were gone, but the random locking up was not. And it was getting worse.
So, I did some of the trouble shooting I had done in the past; created a new user, repaired permissions, repaired the disk, etc. It wasn't fixing anything, just getting worse. I finally did an extended Apple Hardware Test and got the error: 4M0T/4/40000003: HDD-1285
I couldn't find anything on the web about it. So I called AppleCare, they didn't know what it was either. So I took the computer into the Apple Store. They eventually got back to me saying the hard drive and the fan had failed and that they were in the process of fixing it.
However, in the mean time, I moved the MacBook Pro over to the workstation where the iMac had been. Low and behold, within a few hours, I was seeing exactly the same symptoms I'd seen on the iMac. If the Firewire drives were plugged in, the computer would randomly lock up, and again, not even necessarily when the drives were reading or writing. It appears to be completely random. Sometimes specific applications will lock up, like Mail, VLC or System Preferences. Force quitting the application has no effect. The window won't disappear, even if I attempt to log out or shut the computer down. The screen will change to the grey background, but the window will never go away. It'll just sit there with the pin wheel forever. The only option at this point is to force the system to shut down with the power button.
This only happens when Firewire is connected.
I've tried swapping out the cable with no luck, the same problem is true. I have five drives daisy chained like this:
WD MyBook 2TB --> WD MyBook 2TB --> WD MyBook 2TB --> LaCie d2 Quadra v3 2TB --> LaCie d2 Quadra v3 2TB
Now, admittedly, I have never daisy chained, so I don't know if I've made some bad mojo for myself by my device order, or by mixing brands or something, or if it's even possible that maybe one of the drives is faulty and it's screwing things up for me. I just don't know, and troubleshooting is challenging becuase I can't make the problem happen, it just happenes whenever it feels like it.
I have to get this issue resolved. I could switch back to USB, but I'd hate to do that because I spent a substantial amount of money on the drives specifically to avoid using USB
Insight into this would really be appreciated.

Answer 1

I am having the exact same problem. Th eone difference is that on occasion, iTunes downloads my playlists yet not the associated songs in the playlist.