ISO serious help

I've been trying to track down a problem with my DAC seemingly unlocking (for < 1 second) when i'm outputting s/pdif from my computer. When it does, the music stops for this split second.

Today i turned off the flourescent light in my fish tank and the DAC unlocked for that split second. i turned it on and off repeatedly and every time it went either on or off the dac unlocked. I have also noticed the same problem during lightning storms. every time lightning strikes the DAC unlocks. I have also been able to reproduce the problem when plugging an extension cord into the wall socket in an adjacent room. This was an extension cord with nothing plugged into the other end. Apparently Halloween comes early around here.

i experience no problems when i use the dac with my cd player as the transport instead of the computer (utlizing the same coaxial cable)

I would not have a problem with this slight hiccup if it only occured when lightning strikes or the aquarium light goes on and off, but unfortunately it happens completely randomly throughout listening sessions.

I am at a loss here. I am hoping that someone has experienced a similar situation. I spoke with m-audio, who makes the soundcard that i'm using, and they don't know what to tell me. I overclock my CPU and thought that this could have something to do with it. I returned it to its stock settings but nothing changed. Tomorrow i will run a heavy extension cord from another circuit of the house and plug the computer into it to see what happens.

thanks in advance,
kevin