I was listening to some music today (Motley Crue's 1997 version of Shout At The Devil) and I noticed the bass didn't sound right. It sounded like it was cutting off and on at random. I went over to the subwoofer and sure enough the bass was intermittently cutting out. For lack of a better term, it sounded like it was farting air through the ports when it would cut out. Now I'm in a panic, as this subwoofer was a major purchase for me, both for financial and waf reasons, not to mention I have had it for only a month and a half. So I tried a few things... 1.) Thinking maybe the cd was bad I tried a different Cd. Still had problem. 2.) Tried playing a movie. Still had problem. Btw I play cds and dvds throught the same dvd player. 3.) I switched to the tuner and tried playing FM music. Still had same problem. 4.) Shut off receiver (HK AVR-525) and subwoofer and turned both back on. Still had problem. 5.) Moved cable from one sub input to the other. Still had problem. 6.) Now, these next 2 things I did at the same time. I changed the subs auto/on switch from auto to on and changed the bypass filter to off. Now the problem seems to have gone away, and after testing it with different material I put the switches back the way I had them and it still seems fine. So I guess maybe something got "stuck" in the sub amp possibly? And by changing the switches might have made it ok? Because it sounds fine now, although I am still worried. One last thing, something I should have thought of before I guess, but do you have to register the sub to get warranty support? I didn't see anything in the user manual or on the web site regarding this.