One of my BX5 D2 studio monitors emits loud white noise at random times..

I don't think the problem's in tweeter or woofer, because that white noise isn't constant all the time. It's really weird... at times the speaker seems to be working perfectly, then out of nowhere loud white noise is suddenly destroying my ears and I'm forced to turn it off. I've been looking at forums all over the internet and I haven't yet come across to such a problem. I've opened up the speaker and checked the capacitors, they all look normal.. I don't want to give up hope on this speaker just yet... Does anybody have a clue what might be wrong?