I'm having a weird issue with Lion on 2 different machines (2008 Mac Pro, 2011 15 inch Macbook Pro). The first machine was upgraded through several OS versions to Lion, the second came with Lion preinstalled.
The problem manifests whenever I reboot the machines. I get the startup bong and the Apple logo with the spinner. This seems to be up for an awfully long time, but the spinner doesn't ever stop so the machine doesn't hang. But then it spontaneously resets itself and emits another startup bong. The second time it goes through the boot process it's successful and I get to the desktop.
While I can (eventually) boot both machines, there is obviously some issue that needs addressing here. Does anyone know what may be causing a first boot to fail but a second boot to succeed?