I am running 4.0.0.198 on my phone with no issues...
You can get 4.0.3.32 firmware at:
http://www.t-mobile.com/business/pro...6167&class=pda
Click on "System upgrade". It asks you for your phone number... Easy if you follow the instructions, but takes about 15 minutes...
Also helps to change the "Trusted" setting to "Yes" in Settings -> Bluetooth -> Device Properties