Is the Echo Mia messing me up?

I'm asking here, before I tear my system down, in case anyone knows for sure:

Since SONAR came out, I've used it with much satisfaction on five different computers, several SONAR versions, and two or three Windows OS versions.  A constant has been the fairly frequent complete crash of the sound engine, which kills the system sound and requires a reboot.  This usually happens when I have a pile of CPU-heavy synths and plugins running, and/or when I'm quickly changing settings during a looped portion of a fast-tempo song.

Another bothersome thing has been Sonar's refusal, despite any configuration changes, to share the sound engine with another app.  If I have WinAmp, Sound Forge, Vegas, etc, open, SONAR will not start its sound engine.  If SONAR is already open, no other app can make sound and produces an error message saying so.
 
The only piece of gear I've used continuously has been an Echo Mia card I've moved from PC to PC (I know - it's very old and discontinued, but it still sounds good).  I've tried alternate drivers, but the same thing still happens.

I have two options at hand that involve spending no money:
►Swapping the Mia with a 2005-era, still shrink-wrapped M-Audio Revolution 7.1 card
►Using the motherboard's built-in sound chip, Realtek ALC662 6 -Channel High-Definition Audio

Any chance switching to either of these two devices will stop this annoying total sound shutdown?