Can't upload to Arduino Gemma

I recently acquired an Arduino Gemma board and have been trying to test it, but I can't seem to upload any sketches. I've selected the right board in the Arduino IDE, selected the right programmer, and I press the reset button to start the bootloader before trying to upload, but I keep receiving this error:

avrdude: Error: Could not find USBtiny device (0x2341/0xc9f)

and nothing gets uploaded to the board. I've also noticed that the bootloader LED just seems to stay lit and doesn't really "pulse" like the instructions say. Does anyone know how to resolve this issue?


spycatcher2k: Double tap the reset button.

Didn't do anything different and didn't work. The red LED is still on but not pulsing. I tried repairing the bootloader, but I'm having this same exact problem:

So I ordered another Gemma (this time from Adafruit instead of Arduino) assuming that my original was defective. I plugged in my new Gemma straight out of the box and the same problem was happening. But then I tried on another computer and it started working! So I guess the problem actually has something to do with my USB ports not working properly instead of with the board itself... I can program other Arduino boards no problem though, so I'm not sure what the problem is.