Thanks guys.
It isn't dust. Opened it up and it was very clean.
Used the Console Application and found this item in the log when it goes to sleep.
" mDNSResponder: Repeated transitions for interface lo0 (127.0.0.1); delaying packets by 5 seconds"
Does that sound like hardware or software? Has anyone else run into this problem?
thanks again
Brad
[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=192249\")
Actually that entry looks like it might be a result of your computer shutting down / sleeping, but not related to the cause. From my limited knowledge, I'd say that message is saying, "something is cycling the loopback interface on and off repeatedly, and as this is not playing nice with the system, I'm going to delay messages to the loopback interface and see if it calms down"
I just tested this by putting my macbook to sleep by closing the lid, and I got this same message in my console log for every active interface. So I'd say that message is caused by putting the machine to sleep. The mdns responder is a bonjour service (zeroconf networking), so I would venture to guess that the mdns responder is sending out messages on all interfaces that your computer will be going byebye.
In your Console App., click on the top left button labeled "Logs" and you'll see a list of many log files. Scroll down that list and select "system.log," and look for the time when your machine last showed this behavior, you should see some entries referencing sleep, and hibernate like this...Apr 28 09:37:32 HelitackMac kernel[0]: hibernate image path: /var/vm/sleepimage
Apr 28 09:37:32 HelitackMac kernel[0]: sizeof(IOHibernateImageHeader) == 512
Apr 28 09:37:32 HelitackMac kernel[0]: Opened file /var/vm/sleepimage, size 2147483648, partition base 0xc805000, maxio 400000
Apr 28 09:37:32 HelitackMac kernel[0]: hibernate image major 14, minor 2, blocksize 512, pollers 3
Apr 28 09:37:32 HelitackMac kernel[0]: hibernate_alloc_pages flags 00000000, gobbling 0 pages
Apr 28 09:37:33 HelitackMac configd[40]: posting notification com.apple.system.config.network_change
Apr 28 09:37:33 HelitackMac lookupd[7611]: lookupd (version 369.6) starting - Mon Apr 28 09:37:33 2008
Apr 28 09:37:34 HelitackMac kernel[0]: System SafeSleep
Just before the first entry referencing sleep or hibernation, there may be some entries referencing the cause of the shutdown. You could copy anything that looks related and post it here for us to peruse. I'm just guessing here, as there is no such reference on a normal sleep on my machine, but there ought to be such a reference for an unusual event.
Another troubleshooting step would be to see if other intensive use can cause the same sleep, try a cpu intensive transform in photoshop or the gimp, or something else that makes your cpu work hard, and your fan get loud.
If we fail to help you here, I'd recommend the forums over at [a href=\"http://forums.macosxhints.com/]macosxhints.com[/url] where there are a bunch of hyper-knowledgeable mac folks.