Bluetooth hangs up when dialing

[batpot]

I'm having a similar problem w/ a JVC headunit, but I'm using the stock Sprint 6.1 ROM. I also tried a Treo800 running WM 6.1 and it works as it should.
For me, whenever I dial or receive a call, it drops bluetooth connection immediately, but doesn't drop the call (I can still use the phone itself).
What's odd though, is if I'm connected to the head unit playing audio files, then the headset profile works as it should.

Additionally, xda forums had a similar thread, and showed some registry hacks that I tried, but didn't work for me.
Original thread here (post count not high enough to post links, sheesh):
forum.xda-developers.com/showthread.php?t=591322

hacks summarized here (I modified some of the notes for the settings on my phone):

1. Install a local Registry Editor

2. Enable RAPI and user provided certificates so a registry editor will work

i. Navigate to HKLM\Security\Policies\Policies\
ii. Click "Values" soft-key
iii. Change "00001001" value to 1 (decimal) (recovery note: default is 2)
iv. Change "00001005" value to 40 (decimal) (recovery note: default is 16)

3. Reboot device.

4. Modify the HandsFree plug-in:

HKLM\Software\WIDCOMM\Plugin\HandsFree
i. Change SupportedFeatures to 45 (recovery note: default is 1383)
ii. Add value HFBDA binary, set to same value as LastConnectedBda
iii. Add value HFDeviceType decimal 2

5. Modify the WIDCOMM bluetooth general settings:

HKLM\Software\WIDCOMM\BtConfig\General
i. Change bdaddr to (no value) (on my phone, this keeps resetting itself to its default after a soft reset)
ii. Add value DisableReopenAudio decimal 0 (recovery note: some phones have this key already, with default decimal value 1)

6. Reboot device

EDIT: OK, I found I have Version 1.9.0 build 4800.