I am not an expert, but from my experience the two times I had my UG007 freeze (and the times I had my MK802 II's HDMI output *blink*) I had them running on a single USB power source, with multiple USB accessories leeching power back out. For example, an unpowered hub, with a keyboard and mouse plugged in.
I would recommend getting a self-powered hub, if at all possible (which can be as simple as a hub that has two USB ports for input, one for data+power and the other for just power). Sort of pre-amplifying your accessories you are attaching.
You also could switch to using the power adapter the UG007 comes with, which provides 4x the Amp's as a straight USB connection. This could improve the stability.