This was driving me nuts, I put in a larger SSD today going from a 120GB to a 240GB and blew away my Windows Partition to make the process easier to expand OS X, etc. After installing windows again the only thing in device manager that wouldn't load was the Bluetooh USB Host Controller. Tried every package in Bootcamp for version 4.0.4033 and 5.0.5033 and no luck.
Finally came across this site:
http://ron.dotsch.org/2011/11/how-to-get-bluetooth-to-work-in-parallels-windows- 7-64-bit-and-os-x-10-7-lion/
1) Basically Right click the Device in Device manager, Go to Properties, Select Details tab, Choose Hardware ids from Property Drop down. Copy the shortest Value, his was USB\VID_05AC&PID_8218
2) Find your bootcamp drivers and under bootcamp/drivers/apple/x64 copy AppleBluetoothInstaller64 to a folder on your desktop and unzip it. I use winrar to Extract to the same folder.
3) Find the files that got extracted/unzipped and open the file with notepad called AppleBT64.inf
4) Look for the following lines:
; for Windows 7 only
[Apple.NTamd64.6.1]
; No action
; OS will load in-box driver.
Get rid of the last two lines the following:
; No action
; OS will load in-box driver.
And add this line, paste your numbers in you got earlier for USB\VID_05ac&PID_8218:
Apple Built-in Bluetooth=AppleBt, USB\VID_05ac&PID_8218
So in the end it should look like the following:
; for Windows 7 only
[Apple.NTamd64.6.1]
Apple Built-in Bluetooth=AppleBt, USB\VID_05ac&PID_8218
5) Save the changes
6) Select Update the driver for the Bluetooth device in device manager and point it to the folder with the extracted/unzipped files and it should install the Bluetooth drivers then.
Updated:
Just found this link as well that does the same thing:
http://kb.parallels.com/en/113274