First BSOD since I installed Windows7 three months back

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The BSOD seems to be caused by your antivirus.

Code:

*******************************************************************************
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*                        Bugcheck Analysis                                    *
*                                                                             *
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Use !analyze -v to get detailed debugging information.

BugCheck 7A, {fffff6fc50017990, ffffffffc0000185, 107f28880, fffff8a002f32c8b}

*** WARNING: Unable to verify timestamp for EX64.SYS
*** ERROR: Module load completed but symbols could not be loaded for EX64.SYS
Probably caused by : EX64.SYS ( EX64+193ac3 )

Followup: MachineOwner
---------

Code:

fffff880`0b9b6b00  fffff880`02ce1d00Unable to load image \SystemRoot\System32\Drivers\SRTSP64.SYS, Win32 error 0n2
*** WARNING: Unable to verify timestamp for SRTSP64.SYS
*** ERROR: Module load completed but symbols could not be loaded for SRTSP64.SYS
 SRTSP64+0x3fd00

Norton tends to cause BSOD-s and several other issues. I would recommend uninstalling it with the Norton Removal Tool and replace with Microsoft Security Essentials To Test.

• Norton Removal Tool

Make scans with the following:

-Kaspersky TDSSKiller

• Anti-rootkit utility TDSSKiller

-ESET online scanner

• Free Online Virus Scanner | ESET

In addition, run the malicious software removal tool and WDO:

• Malicious Software Removal Tool
• Windows Defender Offline

Microsoft Security Essentials.

Recommended from a strict BSOD perspective, compatibility & stability compared to other antiviruses/internet security software. It is free and lightweight:-

• Microsoft Security Essentials - Free Antivirus for Windows
  
  • Malwarebytes : Malwarebytes Anti-Malware removes malware including viruses, spyware, worms and trojans, plus it protects your computer
    
    • Good and Free system security combination.
    • How to Scan Your Computer With Multiple Antivirus Programs - How-To Geek
    
    
  
  

   Warning

Do not start the free trial of Malware Bytes; remember to deselect that option when prompted.

Run a full scan with both (separately) once downloaded, installed and updated.
Perform a System File Check:

1. Click on the start
2. Type CMD on Search
3. Left click and Run as Administrator
4. Type SFC /scannow

Full tutorial here:

• SFC /SCANNOW Command - System File Checker

Disk Check on your hard drive for file system errors and bad sectors on it:

• Disk Check

Reduce items at start-up. Nothing except anti-virus is required plus improves the time for logging in windows.

• Startup Programs - Change
• Troubleshoot Application Conflicts by Performing a Clean Startup

If the above does not bring stability, test RAM in the following manner:

Take memtest. Run for 8 passes and test each stick in a know good slot for an additional 6 passes.

• RAM - Test with Memtest86+

The goal is to test all the RAM sticks and all the motherboard slots.

Check your motherboard manual to ensure the RAM sticks are in the recommended motherboard slots. Some motherboards have very specific slots required for the number of RAM sticks installed.

If you get errors, stop the test and continue with the next step.

1. Remove all but one stick of RAM from your computer (this will be RAM stick #1), and run Memtest86 again, for 7 passes.

*Be sure to note the RAM stick, use a piece of tape with a number, and note the motherboard slot.

If this stick passes the test then go to step #3.

2. If RAM stick #1 has errors, repeat the test with RAM stick #2 in the same motherboard slot.

*If RAM stick #2 passes, this indicates that RAM stick #1 may be bad. If you want to be absolutely sure, re-test RAM stick #1 in another known good slot.

*If RAM stick #2 has errors, this indicates another possible bad RAM stick, a possible motherboard slot failure or inadequate settings.

3. Test the next stick of RAM (stick #2) in the next motherboard slot.

*If this RAM stick has errors repeat step #2 using a known good stick if possible, or another stick.

*If this RAM stick has no errors and both sticks failed in slot#1, test RAM stick #1 in this slot.

4. If you find a stick that passes the test, test it in all the other motherboard slots.

If Part 2 testing shows errors, and all tests in Part 3 show errors, you will need to test the RAM sticks in another computer and/or test other RAM in your computer to identify the problem.

In this way, you can identify whether it is a bad stick of RAM, a bad motherboard, or incompatibility between the sticks.

   Information

Errors are sometimes found after 8 passes.

   Tip

Do this test overnight, before going to bed.