Well VDJ cant be that "crappy" as it's working when serato intro is not.
Anyway, try a good quality short usb cable, 3ft max, power drain on longer cables exceeds the max of the 500ma that the usb port will provide in USB 2 mode (yes i know that usb ports can provide more but the device only requests 500ma) , as it happens the USB interface/driver in VDJ 8.1 is very forgiving for devices that disconnect/reconnect due to power issues.
Another tip is clear out serato's settings in your registry, uninstall serato and delete the install folder from c:\program files\serato
then reinstall serato. please note that serato intro does not like windows 8.x, upgrade to win 10 for best function, if you are using MAC version then i cant help, i dont have the serato on mac.
One thing that was mentioned to me is the latest serato dropped support for older pioneers in the intro package, i however have not checked this, so dont quote me.