Windows 7: Removable HDD causes BSOD.....Help!!!

Hi all,

I've just installed a new system for a freind which, at his request, includes an internal removeable HDD (mounted in a caddy)

When I first installed Windows (with AHCI selected in BIOS beforehand), the drive could be installed (ie "switched on using a key on front of the caddy) and Windows 7 would recognise a new drive and pop up the "Autoplay" screen. Likewise, when I when to "eject media" I could select, and power it down before phyically removing it....all with no problems

HOWEVER...!!!

A few hours later, I've installed some programs, documents, Windows 7 updates etc and if I try to install the drive whilst already in Windows, I get a BSOD and the system reboots. After the reboot, the drive is present and correct and can be removed as before. If I try to install it again.....same BSOD

FYI, once rebooted after the BSOD I have it showing in Disk Management as follows;

Disk 1, Basic, "BackUp (F"
NTFS
Healthy (Primary Partition)

Under "Policies" I have it set to "Quick Removal"

I still have AHCI selected in BIOS and my Registry reflects that Windows 7 has the AHCI drivers loaded

I'm not expert by far so would appreciate any help you guys might be able to offer!

The ONLY thing I can think of that may have caused the change in behaviour was that I changed some drive letters via Disk Management and also had an external USB drive set to "Active" so I changed this using dskmgr

Should my System Reserved partition on the boot drive have a drive letter? I don't recall having seen it before but it now has "E:" attached to it...I think the same as this troublesome removeable drive had at installation....could this be anything to do with it??

Any help VERY much appreciated guys!

In addition to the above, I have now just noticed that the "system reserved" partition is also showing as drive E: under "Computer" in Explorer.....what an earth could have caused that?!?