I am not using a USB hub, not using external hard drives or thumb drives my laptop is a high end ASUS i7 Processor running windows 10.1 with 16GB of RAM and a 1TB 7200 rpm hard drive running Serato 1.9.0 The problem started when I was running Serato DJ 1.8.0 and has continued with the new version and the new 1.06 firmware of the Pioneer DJM S9 mixer.
Now the problem has been reported on others using Macbook Pro Laptops as well so it is an issue that is prevalent for this mixer in particular and reading the forums sounds like it might not be the only product in their line that suffers similar problems. It could be specifically the Serato DJ software as the Rane 62 mixer is capable of Using the regular Serato Scratch Live Software versus needing to use the Serato DJ software and it's possible that one is more stable overall. Or it could be something that Pioneer is having problems with being that this is their first time working with Serato. They haven't worked with Serato very long so haven't had experience troubleshooting many different issues just yet. Perhaps their firmware just needs an update and the Engineers just need to figure out what is happening.
This is very sad being that I basically paid over $1800 for a mixer that as of the moment I can only use at home for personal use or that I have to use in the field with a back up plan ready in case it starts glitching. IE make an announcement while I quickly reset it by unplugging the USB cable and plugging it back in etc. I put in an official help request on the Pioneer forum at:
https://forums.pioneerdj.com/hc/en-us/community/posts/204504293-Huge-Glitch-Problems-with-Serato-and-Pioneer-DJM-S9
and another one on Serato's forum at:
https://serato.com/forum/discussion/1556794#new
I love the overall features and ease of use of the mixer, just wish it didn't have this glitch as it is a deal breaker.
https://www.youtube.com/watch?v=jh2dfk6cwzs