Sonar X2 works great for me too (except minor issues, like the bad display of the peak markers in the clip pane).
It is installed on a laptop HP DV7 (i7 720 QM processor and Win 7/64).
So, it is a mass market computer, but i use it only for Sonar (no internet, no antivirus, etc), and every unnecessary feature or device is desactivated (blue tooth, wi fi, internal sound device, etc), and i take care with the IRQ my sound card is plugged on.
And also, I am very careful with plugs (for me external plugs are less and less useful, since the included plugs are now covering almost all my needs - the PC4S, 1176, Concrete Lim, Breverb, Sonitus, PC2A).
When i read about very strange issues i don't have at all, i also think that it must have something to do with hardware (and software conflicts or compatibility).
For me, X1, and now X2, have been great improvements of Sonar (i began with Sonar 4 studio).
Wish it will be the same for you all !...
Thierry
Nice, France