I've discovered an issue with my late 2010 iMac when using Home Sharing in iTunes. When, using Tunes (10.4) and transferring a film from my Mac mini's shared Home Sharing library, the iMac always experiences a hard crash (OS X locks up telling me I have to power off and on again). At first I thought it was an issue with the iMac's OS, but found it's specific to my iMac hardware itself. I discovered this as: Issue occurred when using a Lion OS on external hard drive on iMac (OS 1) Issue occurred when using iMac's hard drive's OS (OS 2) Issue didn't occur on MacBook Pro (OS 3) Issue didn't occur when using the Lion OS from external hard drive on MacBook Pro (OS 1) As you can see the issue seems specific to the iMac as when trying a different machine (using either that machine's OS or an external hard drive bootable OS that had issues on the iMac), the issue doesn't occur. All machines are using OS X Lion and fully up to date. Copying large files over AFP and FTP doesn't have this issue. Just when copying larger files via Home Sharing, and only on my iMac, no matter if I use it's own OS or one that works fine on other hardware that's on an external hard drive. Any ideas how to resolve this?