Same problem here
I tried to look through the logs. The only thing I can find is in kernel.log that the last entry before my Mac Mini locks up is:
Jul 24 22:36:52 RoyGs-Mac-mini kernel[0]: Ethernet [AppleBCM5701Ethernet]: Link up on en0, 1-Gigabit, Full-duplex, Symmetric flow-control, Debug [xxxx,xxxx,xxxx,xxxx,xxxx,xxxx]
After hard power-off, Os X Lion boots as it should showing that the next line would have been:
Jul 24 22:49:28 RoyGs-Mac-mini kernel[0]: [ffffff800884f500][AppleMultitouchDevice::start] entered
I really don't know if this is of any help to solve this problem. I must admit I am pretty clueless about the boot process. This is the 4th time this happens.
HDMI on a plasma TV. I know there is no video signal because my TV says "WIDE" just below "HDMI" when it receives a signal.
I also know this wasn't a problem with the previous version of Os X.
Here is the rest of the log when the machine started successfully:
Jul 24 22:49:30 cm-84 kernel[0]: Sound assertion "0 == fAudioEngineArray" failed in AppleHDADriver at line 4493 goto Exit
Jul 24 22:49:30 cm-84 kernel[0]: Sound assertion "0 != result" failed in AppleHDADriver at line 4475 goto handler
Jul 24 22:49:30 cm-84 kernel[0]: Sound assertion "0 != result" failed in AppleHDADriver at line 4065 goto handler
Jul 24 22:49:30 cm-84 kernel[0]: Sound assertion "0 != result" failed in AppleHDADriver at line 4075 goto handler
Jul 24 22:49:30 cm-84 kernel[0]: Sound assertion "0 == fAudioEngineArray" failed in AppleHDADriver at line 4493 goto Exit
Jul 24 22:49:30 cm-84 kernel[0]: Sound assertion "0 != result" failed in AppleHDADriver at line 4475 goto handler
Jul 24 22:49:30 cm-84 kernel[0]: Sound assertion "0 != result" failed in AppleHDADriver at line 4065 goto handler
Jul 24 22:49:30 cm-84 kernel[0]: Sound assertion "0 != result" failed in AppleHDADriver at line 4075 goto handler
Jul 24 22:49:31 cm-84 kernel[0]: IOHIDSystem: Seize of IOHIDPointing failed.
Jul 24 22:49:31 cm-84 kernel[0]: IOHIDSystem: Seize of AppleMultitouchHIDEventDriver failed.
Jul 24 22:51:32 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 24 22:51:41 cm-84 kernel[0]: AppleBCM5701Ethernet: 0 1 BCM5701Enet::replaceOrCopyPacket worked after N tries
Jul 24 22:52:04 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 24 22:54:03: --- last message repeated 1 time ---
Jul 24 22:54:56 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 24 22:56:46 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 24 23:09:15 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 24 23:11:00 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 24 23:11:30: --- last message repeated 2 times ---
Jul 24 23:15:57 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 24 23:16:33: --- last message repeated 1 time ---
Jul 24 23:23:01 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 24 23:39:12: --- last message repeated 1 time ---
Jul 24 23:39:12 cm-84 kernel[0]: (default pager): [KERNEL]: ps_allocate_cluster - send HI_WAT_ALERT
Jul 24 23:39:12 cm-84 kernel[0]: macx_swapon SUCCESS
Jul 25 00:05:12 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 25 00:06:23: --- last message repeated 2 times ---
Jul 25 00:06:23 cm-84 kernel[0]: IOSurface: buffer allocation size is zero
Jul 25 00:06:53: --- last message repeated 2 times ---
Audio is working fine despite audio errors, through FireFly, an external FW2 Audio Interface. I don't know about the other errors/warnings, but the system is up and running so I guess those can safely be ignored.
No kernel panics reported either, so it seems I am impatient or that there is a deadlock during bootup for some reason. (Regarding impatient, I have been waiting at least 15 minutes at one occasion.)
[EDIT:] I forgot to mention that I don't need to reset the PRAM to make the computer boot properly. It suffices to hard power-off and then turn the power back on.