Hi!
I came across this problem just today - When i try to play a track in Serato DJ while the DDJ controller is not plugged in, it works perfectly fine.
Whenever i connect the controller, serato gets slower, the tracks wont play and the soundwaves wont show.
The smaller, thin sondwave (where it says drag song here) on top of where the big soundwave should be, is the only soundwave that shows.
At first, the controller wouldnt even connect with serato but eventually i got that going.
If i press play with the computer mouse, the play button turns blue but the song wont play, same goes when i press play on the controller.
After a couple of clicks, serato will freeze and i have to ctrl-alt-delete it.
I tried updating serato to 1.9.3 and i also downloaded the latest firmware and even downloaded the 1.100 driver to the DDJ - NO LUCK
I posted this at the serato forum aswell, but i think the problem lays within the controller.
Help would be veeery much appreciated - Thanks!
Dan