Windows 7 x64 Switches Itself Off!

Hi, Now if anybody can help I'd appreciate it!

My system switches itself off by itself, not during the day but early morning and only once. My event log has the following for this morning...

The system is entering sleep.

Sleep Reason: Application API

The browser has forced an election on network \Device\NetBT_Tcpip_{E869950A-E304-4E84-AFE3-15E615C2279A} because a master browser was stopped.

The TCP/IP NetBIOS Helper service was successfully sent a stop control.

The reason specified was: 0x40030011 [Operating System: Network Connectivity (Planned)]

Comment: None

The TCP/IP NetBIOS Helper service entered the stopped state.

The system time has changed to ‎2010‎-‎10‎-‎15T06:08:40.500000000Z from ‎2010‎-‎10‎-‎15T06:08:44.387695300Z.


The previous morning it shut itself down with this in the event log....

The process C:\Windows\system32\winlogon.exe (user) has initiated the power off of computer user-PC on behalf of user NT AUTHORITY\SYSTEM for the following reason: No title for this reason could be found
Reason Code: 0x500ff
Shutdown Type: power off
Comment:

User Logoff Notification for Customer Experience Improvement Program

The Event log service was stopped

The Windows Update service entered the stopped state.

The Group Policy Client service entered the stopped state.

DHCPv6 client service is stopped. ShutDown Flag value is 1

DHCPv4 client service is stopped. ShutDown Flag value is 1

The DHCP Client service entered the stopped state.

The Diagnostic Service Host service entered the stopped state.

The NVIDIA Driver Helper Service service entered the stopped state.

The Diagnostic Policy Service service entered the stopped state.

The Power service entered the stopped state.

And the morning before that i got this...

The process Explorer.EXE has initiated the power off of computer user-PC on behalf of user user-PC\user for the following reason: Other (Unplanned)
Reason Code: 0x0
Shutdown Type: power off
Comment:

The process C:\Windows\system32\winlogon.exe (user-PC) has initiated the power off of computer user-PC on behalf of user user-PC\user for the following reason: No title for this reason could be found
Reason Code: 0x500ff
Shutdown Type: power off
Comment:

May I say what I have looked at...

Firstly anything scheduled in my programs I am running or task scheduler
Bios for power options
Windows power options
Computer scanned for viruses
Checked power supply but I'm sure it's not this as it only happens once a day at a similar time.
The only thing I can think is it coincides with updating windows.

Can anyone help it's killing me! :)

This looks like a malware/ trojan or a PSU problem. Run a MBAM scan, if theres a spare PSU, check with that.

In any case, since it coincides with windows updates, turn off automatic windows updates first.

Turn off Windows automatic updating in Windows 7

If the problem goes away, we know it has something to do with the updates.

I would also disable everything that has to do with NetBIOS - I have never seen anything useful from this stuff and lots and lots of problems.

Thanks guys how do disable netbios? I had disabled windows updates when i re-installed and since (somehow) windows updates got enabled by itself, hence installing all the updates without me knowing then the problems. Already done an MBAM scan results were 0 problems

Intel Core 2
4GB RAM
Biostar G31-M7 TE Motherboard
Windows 7 x64 Ultimate

I've tried disabling the Realtek Network adapter power savings feature to see if that helps

I appreciate your thoughts but why would an erratic PSU only shutdown once during the same hour of the day?