Post pics of the pcb layout or a portion.
Loop area refers to the area the signal goes... also, it must return (hence return path). Normally you'd have a solid ground plane for your various return currents.
Low speed < 1mhz signals can diffuse widely over area and go around crappy grounding without being a showstopper. But most digital logic has edge rates ~1-2ns which is going to be a different story.
At fast speeds >100mhz return paths are very tightly concentrated within the ground plane right underneath (or adjacent). Breaks or cutouts in the plane are bad news (ground plane discontinuities)
If your grounding sucks, the signal still has to have a return path, and it will find one... it may be another signal.
Different USB hub chipsets will vary in their tolerances for how much timing allowance they will give during enumeration, how many times control transfers can time out, etc... Also, pcs vary in the physical signal connection from the USB port on the PC case to the motherboard. When in doubt, plug in as close as possible.
You could also be loading down the 5v supply excessively, or the hub may enforce power policy per the USB spec (few do, for compatbility)
There is really a lot of reasons you could be seeing this, more info!