Lead 1010 Black Box Wont Work with USB Extension?

USB by design works best on short leads. Higher leads have higher internal capacitance and inductance, which slews the high frequency USB signals too much. This holds true for most USB devices.
The second factor is the USB port of the PC itself. Some do not deliver enough current and the long cables cause too much of a voltage drop.
Also the drivers (hardware) of the D+ and D- signals may be weaker on some PCs.
And lastly, long cables are more susceptible to EMI interference.

So basically, we recommend keeping it around 4 feet. If you really need it longer, investing in a "powered USB Hub" or a "powered Active USB extension" with a sufficiently long cable will work better than just a passive extension, but be aware that it doesnt negate the negatives entirely, you may still suffer communications issues leading to ruined workpieces and broken endmills

If you get either of those make sure they come with their own power supply, cheaper ones sometimes has the power input port, but doesnt include the power supply, or worse, just power off the USB port itself (same as above, long cable drops too much power, and you are still in the same boat)

Extra reading: Maximum length of a USB Cable? and USB Cable Length Limitations And How To Break Them

 

I purchased a 12 foot usb from Fry's electronics and so far it has worked well for me. But, I have been known to be lucky at times. My cable runs from the computer into my cabinet the CNC is on top of so it is probably 2-3 feet from any other cabling and the power cable from my router goes straight up to the ceiling so there is a lot of separation.

 

Less "luck" and more likely just a solid set of USB tranceivers on that motherboard of yours (;