Windows 7: PC randomly turns off

My OS is Windows 7 ultimate 64bit

I checked recent errors in the event viewer program and found this:

Log Name: Application
Source: Application Error
Date: 6/11/2011 5:32:04 PM
Event ID: 1000
Task Category: (100)
Level: Error
Keywords: Classic
User: N/A
Computer: Maniatis-HPC-PC
Description:
Faulting application name: SearchIndexer.exe, version: 7.0.7600.16385, time stamp: 0x4a5bcdd0
Faulting module name: ESENT.dll, version: 6.1.7600.16385, time stamp: 0x4a5bda4f
Exception code: 0xc0000005
Fault offset: 0x0016257b
Faulting process id: 0xdb8
Faulting application start time: 0x01cc287f0195a620
Faulting application path: C:\Windows\system32\SearchIndexer.exe
Faulting module path: C:\Windows\system32\ESENT.dll
Report Id: 3f768f40-9472-11e0-9703-001bb9ddd3dc
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Application Error" />
<EventID Qualifiers="0">1000</EventID>
<Level>2</Level>
<Task>100</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2011-06-11T21:32:04.000000000Z" />
<EventRecordID>31157</EventRecordID>
<Channel>Application</Channel>
<Computer>Maniatis-HPC-PC</Computer>
<Security />
</System>
<EventData>
<Data>SearchIndexer.exe</Data>
<Data>7.0.7600.16385</Data>
<Data>4a5bcdd0</Data>
<Data>ESENT.dll</Data>
<Data>6.1.7600.16385</Data>
<Data>4a5bda4f</Data>
<Data>c0000005</Data>
<Data>0016257b</Data>
<Data>db8</Data>
<Data>01cc287f0195a620</Data>
<Data>C:\Windows\system32\SearchIndexer.exe</Data>
<Data>C:\Windows\system32\ESENT.dll</Data>
<Data>3f768f40-9472-11e0-9703-001bb9ddd3dc</Data>
</EventData>
</Event>
Any suggestions?

Hi.
If you have any minidumps please follow these steps http://www.sevenforums.com/crashes-d...tructions.html
Those are the instructions how to upload a minidump.
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In meantime check ur temps,with Core Temp
Or in BIOS,how? restart,repeatedly click delete or any other appropriate key until you see the enter setup message,check in there the CPU and System temps.
Also write ur complete system specs,as memory,cpu,graphic card,psu etc.

Windows 7 ultimate: Emachines T5234

Processor: AMD athlon(tm) 64 X2 Dual core
Processor 4000+ 2.10GHZ

Installed memory (RAM): 4.00 GB

System type: 32-bit operating system

Ur newest minidump points to Ntfs.sys and the oldest to ntkrnlpa.exe.
So please for first step remove avast from ur system,clean any remainings fragments with http://www.piriform.com/CCLEANER
Download and install MSE http://www.microsoft.com/security/pc-security/mse.aspx
Then do a HD Diagnostic and a Memory Diagnostic test.
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Please post back with any results!