Possible bad USB block erupter

[brom]

I have a USB block erupter for which the led continually flashes on and off when plugged into my computer.  I have had no luck starting the miner with bfgminer or cgminer; the message I am receiving is /dev/ttyUSB0 is already in use by another process.  I have tried 3 computers, all with no luck.  I was wondering if anyone has had this issue, or knows what could possibly be wrong with the device.  Thanks!