What VFD are you using?
Are all your stepper signal and control cables screened and earthed to the same point?
What Spindle do you have?
I it earthed and the cable screened and earthed?
Some don't like using Laptops for CNC machines ( me included ) Do you have a reasonable spec PC to test with?
USB can be susceptable to EMI. screened USB cables are available, I think ( no experience , I use ESS)
Nothing is overheating?
I have one fan blowing in and another sucking out to ensure good airflow in my case.