Help needed with PC/DAC


My Dell computer keeps rejecting my DAC (usb) and returning to its default factory sound outlet ("Realtek High Definition Audio"), which is definitely lower fidelity.
I have tried to find someone (here on Maui) competent to set up for me, but failed so far.
This has happened with 2 different Teac 301 DACs, so I suspect it is a computer issue.   The sounds are already downloaded on a big external hard drive (NOT livestreaming). 
Any advice appreciated.
jcazador
may want to consider turning OS updates off.   dumps my drivers everytime and resets to the realtek card.  annoying.  
thanks paulsax, good to know I am not alone
my plan now is to duplicate all the music on the external hard drive onto a new external hard drive, and then use my spare computer to play it to the dac/preamp/amp/speakers
completely disconnected from internet
3 years later, just wanted to explain that my problem was solved by installing a $10 POWERED USB hub between computer and dac.