I have the same problem with the Network Space 2. I called LaCie, but they say it must be a problem with iTunes even though they claim plug and play support with iTunes as part of their marketing for the product. Plug and Play by definition means that there should be absolutely no tinkering around with any settings anywhere, it should just work (or it should make the necessary changes itself when the "Mutimedia Service" checkbox is checked in the Network Assistant browser-ware that comes with the drive). I've tried accessing the shared music from 2 different computers: a Macbook Pro running Snow Leopard and iTunes 10 and an iMac G5 running Tiger and iTunes 9. All have the most recent updates. I can access everything on my PS3, but in iTunes, the shared playlist shows up, but I get the same error everyone else has.
Epic Fail on LaCie's part, and Epic Fail on Apple's part for allowing this product to use iTunes as a selling point when it clearly doesn't live up to its claims. Apple gets a lot of grief for it's "control" issues, but that's why we normally love Apple cause everything usually does just work like its supposed to. My advice to Apple... look into this issue and either help LaCie figure it out, or disallow them their iTunes marketing scam. I bought this product specifically for its claimed iTunes integration. This reflects poorly on Apple as nobody (including me) seems to know if its LaCie or iTunes causing the issue (I'm inclined to believe it's LaCie, but then again, I have no issues accessing it via my PS3). Home networking is becoming big business, don't leave those of us who spend a lot of money on music, computers and peripherals out in the cold with no way to connect it all and have everything accessible throughout our home network. PS. I would be using the Apple TV if it allowed me to attach external storage to keep all my music in one place and accessible as shared media on my home network.