Maybe you can disable Magix in Volume Mixer and/or Control Panel if it shows up as a separate audio device.  In Volume Mixer just right click on the little speaker icon in the taskbar tray and chose (alternately) Playback Devices and Recording Devices and disable there.

You can disable drivers in Device Manager too.

Guys I could not find it in the device manager.  
 
I took the draconian step of uninstalling Sound Forge until I can figure this merde out.  That fixed it.  
 
Too bad, the new Sound Forge is 64 bit so my UAD plugins worked with it.  

Those creeps.  Few things piss me off more than software companies taking control of things they have no business with on our computers to make life "easy."  Like for instance, those frickin' automatic updates.
 
Sorry, it's late.  Good luck figuring out a work-around, space_cowboy and let us know what it is.  I was considering getting the 64-bit Pro version when it comes out, but I sure don't need the kind of trouble you are having.

BRain 
There has to be a way to install Sound Forge 12 and not install the drivers.  Their hijacking of my drivers messed the timing up.  
 
Everyone else - thanks for the suggestions.  I uninstalled Sound Forge 12 and made sure the UA drivers were the only options.  Everything works right afterwards.  
 
I recorded a guitar riff of 1/16th and 1/8th notes (plus some rests), A 1/4 note counter riff on a separate track, and some chords (whole notes) on a third.  For 11pm, it was danged close!  
 
Again, thanks all!

Ya know - 
Why is Magix installing drivers at all?  They did not make any of the hardware.  If someone like Bitflipper could chime in... 
 
It was my opinion that drivers were needed for the various devices that existed off the motherboard (and probably devices on the motherboard).  I am not sure I understand why a purely software application would need drivers.  Help me Obiwan, you're my only hope.  
 

Ya that's a strange one, I have a basic version of Sound Forge came with a Sony turntable and it didn't install those drivers. 
Possibly during install there's a checked box that needs un-checking? 
 
This shows once again how important good drivers are. And how important it is to perform a loop back test so your not pulling your hair our=t wondering why your songs suck. 
 
Here's my little loop back experiment where I tried the different drivers , clearly shows ASIO wins. 
 

Johnny
I switched to RME Hammerfall converters maybe 15years ago, with a light pipe connection from their DIGI 9652 (I think) to my D8B console.  I have been a big believer in ASIO for at least that long.  
 
But as good as ASIO is, it really requires the drivers to be fast as well.  
 
I recently bought a UA Apollo rack because after like 10 years and constant use, my RME FF800 just quit.  I like the concept of Unison Technology on the UA, but it is danged hard to beat RME's drivers.  I could routinely get round trip latency of 6-8msec.  If you think about that number, that is like playing electric guitar and standing 6' from your amp.