Unable to locate MBR or HDD until system shut off for a few hours

Apologies if this is in the wrong forum, this is my first time here. If this post is too long, I can try and condense it.

I usually leave PC in sleep mode, last night was no exception. I am used to it occasionally turning itself back on every few days (not sure why) so no surprise to see lights on my comp when I woke up. However, the screen was black with white text, with an error message something to the effect of the system being unable to locate the boot drive. Restart did nothing. I went into BIOS to swap my other internal HDD into boot drive but there's no Master Boot Record on it so the BIOS only saw my primary drive and DVD drive.

I booted into Windows 7 DVD and tried to auto repair which didn't work after reboot. Trying to recover from system restore gave me an error. I attempted to do an in-place upgrade with Windows 7 to perhaps rebuild the MBR but it wouldn't let me use the upgrade option since I needed to be within Windows. Tried the custom install, it didn't even recognize my main HDD, it only saw my lesser 500GB WD drive and I wasn't about to choose to overwrite one of my partitions.

I shut down the computer and went back to sleep perplexed. I woke up, turned on PC one last time (Was about to go out and buy a new HDD to install Windows 7 to so I could try and recover my missing HDD's files). Interestingly enough, the system asked me if I wanted to boot into safe mode because it was shut down improperly. Now it boots into Windows just fine with no problems.

What's going on? Was told at electronic's store that it could be a fault SATA connector on my Mobo, meaning I'd need to replace the whole thing. Could it be the (4 month old) HDD? What else could it be? Why was the system fine after it had been off for awhile rather than through countless hard and soft reboots? :confused:


Excellent Member
Microsoft Community Contributor
Do you let your system hibernate?

You may want to check into why it is waking up on its own.

If it only happened once, I wouldn't worry about it too much, but keep an eye on it.

What type of drive is your primary one, as in power saving or normal? You may want to play with some of your power settings to see if it could make a difference.

No, not power saving, just a normal drive. I've put up with my system waking from sleep every so often ever since I installed Windows 7 RC last August - I'm on retail now, on a different HDD, same thing. Not sure how to go about checking on that. You think that might have contributed to this issue this time of the system not being able to locate my HDD until being shut off?

I've played around with power settings, shut off "wake on LAN", ensured browser was closed before sleep, not sure what else I can do.


Excellent Member
Microsoft Community Contributor
I do not know if the waking is associated with the hdd situation.

Something you might try is to shut down all your open programs. Then open a command prompt window and type the following.

powercfg -energy

It will take about a minute and give a report. Make note of where the report is stored.

There are other switches you can use which might help track down the problem so if you type:

powercfg -help

Maybe one of those switches will help, such as the -lastwake one.

Is it possible you have ACPI or chipset drivers missing or not up to date. It's slightly alarming that you have had to tolerate intermittent wake ups.

Is wake on lan turn on?

This website is not affiliated, owned, or endorsed by Microsoft Corporation. It is a member of the Microsoft Partner Program.