Try a different USB cable.
I have some problem like that so I try this step(from xaueious)For Apad Batch 2 (Red LED with camera, 5V) try the old way...1) slide switch off, USB can be plugged in2) holding Menu button, slide switch on3) DONEYou can get this !"RK28USB device"After that you follow the step by step to get upgrade firmwarebillewilliam;16378 said:Go to DEVICE MANAGERBig yellow question mark beside Android phoneRight click Un-install driverRESTART computer - MOUNT aPadNew Found Hardware wizard* Install from specific location*Include this location searchRk Android_ENG/driver/x86/xp/*CANNOT INSTALL THIS HARDWAREHardware was not installed because wizard could not find necessary software