Get BSOD When trying to open Artist. Had same issue with X3LE. Stop code is Memory Management and Bad  Pool Header. Running Windows 10 on Acer Aspire 5247,SSD,I3,4GB, Boss br800 interface. Soundcard is Realtek. Anyone else had this issue? I've unistalled and reintalled programs Drivers etc. ASIO4all v2. What am I missing?

If you are using the internal sound chip as your audio device and ASIO4all too you are bound to have trouble. It may seem to you that spending money on a good audio interface is not cost effective. In reality a few dollars spent on the right hardware will save your sanity. 

Your BR800 will function as a soundcard/audio interface with ASIO.  Uninstall ASIO4ALL and install/re-install the ASIO driver for the BR800.

Reading above I pondered if this unit comes with actual ASIO drivers. Reading all the support pages and manual I see no mention of ASIO,, it actually say's  " Your OS should automatically download and install the drivers "  which leads me to assume these are possibly a WASPI driver or simple what is called "USB CODEX". So ASIO4all might be a alternative, but your still  working sub standard with any of those options. Good audio drivers are the heart of a stable DAW system so the purchase of a proper interface is always the best way to go. 
Obviously the BSOD is not Sonars fault. It's hardware and drivers. 
 
 
From the user manual:  
"You must install the USB driver into your computer before connecting the BR-800 via USB to your computer. The BR-800’s dedicated driver can be downloaded from the Roland website. Roland website http://www.roland.com/ Refer to the Roland website for details on the operating requirements. The program and procedure for installing the driver will differ depending on your system. Carefully read the Readme.htm file included with the downloaded file." 

I believe Johnny is correct on this.
 
This devise stopped supporting ASIO drivers after Win 7.Version 1.0.0.
It seems the Device downloads a Windows friendly Driver if using windows 8 or higher.
Windows 7 was the last known ASIO compliant Driver available.
 
Driver for Windows 10

Your computer automatically downloads the Windows(R) 10 driver from the Internet when a product requiring the driver is connected to the computer.
https://www.boss.info/global/support/by_product/br-800/updates_drivers/b02dd01c-ff72-4a73-bf5a-7d1beb9d9fae/
 
Personally, I would make absolutely positive your not plugged in to a USB 3 port.
I would also run a memory test just to be on the safe side of things.
https://www.youtube.com/watch?v=l4xcK0qXT3g
 
Uninstall the ASIO4ALL driver, power down and then re start.
Run Ccleaner and also use the registry function (make a back up)
 
Try to boot Sonar without ASIO4ALL just to narrow down a possible conflict/problem.
If you are able to open Sonar you know it is ASIO4ALL causing your problems.
Ive had mixed results with A4A. it has worked great in some settings, others, it's reeked havoc.
 
If your Boss tried to download the windows 10 driver (using microsoft's Windows update system)
It could be causing a conflict between drivers.

Thank all of you so much. Gonna try your suggestions. If i'm not back whining I'll be back thanking everyone again

Thanks so much again everyone. Got it working. Uninstalled ASIO4all, disabled realtek, uninstalled and reinstalled br800 and replugged it into USB 2 Instead of the USB3 that it was plugged in to and so far it's working. Now I just have to learn how to work it. You guys made my day!

I have a BR800.  The USB port shouldn't matter as I only have USB3 ports on my laptop.  The readme indicates that it is an ASIO driver.
 
Anyhow, glad you got it working.  I would recommend always using the same USB port if you have it working.

I would suggest either downloading the early acces update for Sonar or waiting u til the release of 2016/11.

If you read the release notes for it you'll note that there are lots of changes to support audio drivers.