iMac shut down by itself

[vslo]

Hi,
I got my mid 2010 imac for about a month...
I always leave it on, and set it to sleep when I am not using. Yesterday I went to bed and made it sleep. Today when I woke up, it was off. I checked if any power break happened, but it didnt. I checked the log, and there just says the hour when I set it to sleep yesterday, and than it starts the todays log. I am very preoccupied that I have a hardware problem.
What could happened with it ?

EDIT
I just Found this at the todays log, about the time I started the imac:

16/10/10 12:28:17 configd[13] Sleep: Platform Failure - AC
com.apple.message.domain: com.apple.powermanagement.sleep
com.apple.message.signature: Platform Failure
com.apple.message.result: Failure
com.apple.message.uuid: 1C6DA3F6-F7B0-4DF0-9E2F-3E96D9B88E06

what does that mean ?

 

[AlphaDogg]

It sounds to me like your iMac got hit by a power surge, and damaged the power supply. Did you have it plugged into a surge protector or a UPS?

 

[vslo]

Yes I do.
Its acting normal now, but I'm afraid it will happen again.

I also found out this line in the log

16/10/10 12:28:03 DirectoryService[15] Improper shutdown detected
16/10/10 12:28:04 kernel systemShutdown false
16/10/10 12:28:18 kernel Previous Shutdown Cause: -128

Does anyone knows what this means ?

 

[vslo]

also found this

16/10/10 12:28:03 kernel Sleep failure code 0x00000000 0x15000000

means what?

 

[mannix87]

could it have been unplugged accidentally? if it happens again, I suggest you have it checked with your reseller/ Apple store.

 

[vslo]

No it couldn't. I checked it.

 

[DewGuy1999]

No idea what the log entries mean, but you could try this:

Intel-based Macs: Resetting the System Management Controller (SMC)

 

[vslo]

Yeah I know. I will try that if this happen again. So far so good. It slept all night long and woke up fine this morning. Thank for your help guys.

 

[DewGuy1999]

Yeah I know. I will try that if this happen again. So far so good. It slept all night long and woke up fine this morning. Thank for your help guys.

If you do it now, before it happens again, it will reset the SMC and hopefully prevent a re-occurrence from happening. If it does happen again after resetting the SMC then a trip to the Apple Store or an AASP would probably be called for.