I've been having some issues where Finder is unresponsive; that is, if I open a finder window and attempt to navigate to a folder, all I get is an eternal spinning circle. I'm unable to open/save documents in other applications as well, such as Chrome or OpenOffice. Same deal; I get the spinning circle, like Finder is waiting for the drive. Somtimes, I'll even get "Application not responding" when I right-click on the finder icon in the dock--if I force-quit Finder, it will either not relaunch or relaunch with the same problems. Restarting seems to resolve the issue temporarily, but I have to do a hard restart--hold down the power button until the computer turns off. Otherwise, I get stuck at the gray spinning circle screen.
I thought this was perhaps an issue with the installation, as there have been some other odd behaviors ever since I pulled this iMac out of the box. So, last night I tried a reinstallation of OS X on top of the existing one--and Finder was completely unresponsive from fresh boot. I went nuclear and reformatted the drive, did a fresh reinstall of OS X and I still have the same problem. So, either there's a bug in 10.7.5 or I have a hardware issue.
Also, I've been having issues with Time Machine wanting to rebuild the backup for this machine every couple of weeks. I'm using a Western Digital myBook NAS, which worked fine for around 2 years with my previous desktop, a PowerMac G5 with 10.5.
And let's not get started on the lack of restore media included with the iMac--the built-in recovery partition would be an acceptable solution, except the OS X install package is not included there. So, instead of a 30 minutes process with a DVD/USB/recovery partition, it took 8 hours to download and install. I would create my own DVD using the Installation Package as found at many sites, except that Lion is no longer available from the App Store. The simple solution would have been to include a 20-cent DVD, as was done with all Macs I've bought previously.