My Macbook howls everynight?

this sounds wierd, but everynight between 6 and 8:30 my computer will howl like a werewolf, it's done so now for about 4 months sometimes it totally catches me off guard and scares the crap outta me. anyone have any clue what program or whatever could be triggering this? i dont have many programs that didnt come with my mac on here (the only ones are soulseek, neooffice, aurora and flip for mac) so if anyone as an idea id like to now and turn that off.

My Macbook howls everynight?trojan

I don't use a mac, so I'm don't know about any features that would cause this. Sounds like some kind of reminder or alarm clock

My Macbook howls everynight?abtuvurys 2005

Umm I'm thinking you could go think about what you've installed in the last 4 months and see if anything is related.

Also check your .wav or sound files to see if there's a "howl" or something and delete the file or/and see what program uses that file.

Does you computer do this when you're on and off the internet or just off? Do you have AIM or something like that installed and maybe have a friend who is on at the times you hear the howl? I could be their "announcement" when they go idle or come on-line.

Other than that you may have to reinstall your programs and start from scratch.
Reg's theory sounds most plausible to me; could also be a sound effect associated with your desktop theme/screensaver. For example, I have an Aquarium theme on mine, and it has different associated sound effects, i.e., a water 'splooshing' sound.
it sounds like its set on a timer or (alarm clock) right click on the bottom of the screen where the time is and reset the settings..click on Properties.Other than that I have no idea.