It's probably the L&M Vega. I also have that light and when it's in use, it totally messes up my wireless computer.

Have you tried it without the light on there? Or like kat suggested, trying the compass away from your bike? Process of elimination should let you figure out what's causing it.

If it does turn out to be the light, you could try what I did to fix my problem. I have a double piece of heavy duty aluminum foil that I wrap around the light as a 'shield' on the side that my computer sits on. It works!