Hi! I had this issue once so far myself. Just like coolrun said ... it seems you can fix this with a work-around - even though being a tedious task - by turning off/on Home Sharing on either device.
When this happened in my setup I decided to turn the Home Sharing off/on in iTunes on my Mac, because I guess it's quicker to key in the password with a real keyboard.
As all the posts show there seem to be various bugs that hopefully will be squished soon by an update.
I am having this exact same problem also.
After a certain time (about 1~1.5 hours) the Apple TV simply loses the connection to the home sharing, and can't "see" the computer any more.
It happens more and more frequently, and no amount of adjusting settings on the computer fixes it.
Awaiting an Apple Genius to solve this problem for us...
For me it's exactly the same.
*MacBook 13,3" (late 2008) connected via ethernet-cable to Airport Extreme (latest dualband model)
*Apple TV 2010
*Airport Extreme as switch/wi-fi router
All network components has fixed ip's and everything is wired, so I can exclude wi-fi problems or DHCP problems.
To reproduce the error situation:
*iTunes 10.0.1 is running on MacBook (latest Snow Leopard)
*Plug in the power cord of AppleTV, it boots up
*On the beginning of this flow, everything works fine. AppleTV can find the mediathek on my MacBook and stream music and videos.
*Then I let everything as it is for some hours. (AppleTV and MacBook are in sleep mode)
*After this, when I wake up AppleTV with the remote, the itunes library is not shown in the "Computer"-Menu on AppleTV, but Macbook is activated automatically. (normally it should reconnect to iTunes)
*Then, it is no more possible to find the itunes library.
*Only when I switch off AppleTV (remove power cord) an switch it on again, the itunes library is found.
I hope, that this will be fixed soon...
I'm having the same issue. I have two of the new ATVs and both do this. I even returned one to the store and got a new unit, it does it as well. Like other, I find if I turn off Home Sharing and turn it back on the issue is resolved.
I've also had problems with Netflix acting the same way. After a certain amount of time, it becomes unavailable...turn Home Sharing off then on and it resolves the problem.
Apple...Please fix this!
Just adding that I experience the same problem. I have an iMac that connects to an Airport Extreme which connects it with the ATV. All via wireless. It works fine but then suddenly it loses the connection to the Computer. The rest of the Internet is still available. I have to restart or reset the ATV to get it working again. I have found another way also. I have a MacBook and if I use this to access the shared library on my iMac it the ATV will also get back access to it. From the looks of it something in between iTunes on the iMac and the ATV shuts down automatically not realising the ATV is still accessing the Home Share. If the Home Share get's triggered again by a 3rd party it comes back to normal. Can somebody test this and confirm?
Well i had the opposite effect.
Switching from wireless to Cat5 cable seems to solve the loosing connection problem.
At least i have no problems since 2 days when i installed the cable.
In the meantime i installed the MacOS 10.6.5 update and rebooted and restarted itunes and everytime i turned on AppleTV i have a connection to my mac library. I let AppleTV ran for some hours and never ran into problems anymore.