my suspicion was with your computer and not the U12, but that should be confirmed before you start messing with your computer. I would install the U12 on another PC to confirm it isn't the U12.
If it's only a problem with the Acer you should start by going direct from the U12 to the DAC (bypass Nadja)
If the problem persists then "disable all" in msconfig.exe startup, and reboot
if that fixes it then you have to incrementally enable each one to find out the offending startup process.
I suppose you can try safe mode next, though I don't know if the U12 can operate in safe mode
If the problem persists then become a software nazi and uninstall "unfamiliars" with extreme prejudice.
Start by getting rid of any antivirus products (unless it's MS Security Essentials)
Check task scheduler and browser extensions/add-ins
Use extreme prejudice until you see the DPC lat checker stay in the green.
In the BIOS you can disable your integrated audio chipset to be sure it isn't somehow colliding with Gustard
If you've ever installed LogMeIn you should try disabling it's mirror driver
