There are a couple reasons that you can experience a Blue Screen of Death (BSoD) when Windows 7 is loading up.
New or Factory Restored Machine
During Windows 7's initial launch it detects devices and loads drivers. If a Hot Swap bay is turned on during this process a BSoD can occur. Make sure that all bays labeled Hot Swap are off during this initial driver installation. Once Windows is loaded and functional you can use the Hot Swap bays as usual.
Sudden Problems With Established Machines
The most common reason for BSoD's during boot up on a machine that's been working fine is that the BIOS has become reset and the SATA channel is not configured properly. The correct setting for the SATA channel in systems with SATA Hot Swap bays (and systems with USB3 Hot Swap Bays) is AHCI. Go into your BIOS setup at boot time and check how the SATA channels are configured. You can determine what type of Hot Swap bay it is by the etching to the right of the bay.
We can provide BIOS setup instructions if you require them. There are several different motherboards in our machines so there are various instructions for doing this. If you need instructions please submit a request via our Helpdesk and provide your system's serial number.
Note: If you are having problems with BSoD's while Windows is running, please see the Testing Memory in Problematic Systems article.