The Lighting Controller

Hi - I have read other posts similar to this but they don't quite explain the problem I'm experiencing.
My show is actually tonight, so I don't think I'll have a solution in time but I'm just curious...

I run lights for a small theatre in South Africa. Last year we purchased 4 LED RGB lights.
I openly admit that they are cheap Chinese models - Versalite PAR64 RGB LEDs
But when we hired the USB DMX cable (100 channel) and hooked everything up I noticed that there was a flash every few seconds.
What bothers me is that it was only on ONE of the FOUR lights. They are all the same model, so what could this be?

We are running the 6.271 beta Show Express suite with Windows 7 ultimate
I tried using a different address for the light, I used different DMX cables and still no luck.
Any ideas?

Oh- and they work fine on a lighting desk.
Strand 200 console 12/24 channel

May be this problem ?
viewtopic.php?f=15&t=1004

I actually solved my problem before the show - turns out the dmx signal was running through a smoke machine that was having some trouble and then feeding into the lights. When I moved the smoke to the end of the chain it fixed the issue. Thanks for the reply though.