The Instruction at 0x referenced memory at 0x The memory could not be read

Question

I receive the following error: 'The Instruction at 0x####### referenced memory at 0x#######. The memory could not be 'read'

Answer

Disable Background Applications

The most common cause of this error is a background application interfering with the game. Please follow this guide to shut down all background applications.

Update your System

1. Source-engine games rely on DirectX to function properly. Please see the Checking DirectX Settings topic for instructions to update DirectX on your machine.
2. Outdated or corrupted sound and video drivers may also cause problems - please see the Updating Drivers topic for instructions to update your drivers for these components.
3. Please follow the links below to update your system's operating system, motherboard drivers, and BIOS:
   • Windows Update at Microsoft.com
   • Motherboard Information and Drivers guide
4. Verify GCF Cache Files to ensure the issue is not related to a corrupted download
5. Some users have reported that this issue may be resolved by running a full system file check to repair damaged operating system files:
   1. Go to the Start button
   2. Select Run...
   3. Enter cmd and click OK to open the command console
   4. Enter sfc /scannow to check your system files
   5. If prompted, repair any damaged files

Disable System Modifications

1. Make sure that you are not overclocking your system.
2. Disable and/or uninstall any refresh rate-forcing programs.
3. Please temporarily uninstall 3rd party video or audio codecs (the K-Lite codec pack is known to cause this issue).
4. If you have an ATI Graphics card, please uninstall ATI-ACE, ATI-SMART, Trueform and Catalyst AI - Disable VPU Recover for testing.

Advanced Troubleshooting Steps

Please reboot and test after completing each of these steps to determine whether the issue has been resolved.

1. Add this launch option in your game's launch properties to test the game in windowed mode: -window +mat_forcehardwaresync 0
   More information about setting launch options can be found in the Setting Game Launch Options topic.
   
2. Page file: Try turning off your system paging file (you have to reboot) and setting your page file for 1x or 2x the amount of RAM being used. This setting can be found under Control Panel > System > Advanced > Performance > Advanced > Virtual Memory
3. If you have an language other than English set for your Operating System, make sure that you are not setting the console key to an character which Steam will not recognize (§ for example is not valid)
4. Disable all IM programs and do not alt-tab to your desktop, swapping the game out may trigger this problem.
5. If you are using two or more memory modules, try running with only one module and see if you still have this problem. Reducing the number of modules will effectively speed up your memory timing. If the game runs ok with one module but not two, then you have a motherboard timing problem and you will need to make some changes. Please read your motherboard manual before making any changes.
   • Relax the memory timing some motherboards have "conservative" timing or you can manually increase CAS and increase prefetch. If CAS is set to 2.0 increase it to 2.5. If Prefetch is set to 6, increase it to 7 or higher (up to 11).
   • Slightly increase the memory core voltage if your motherboard supports this option, consult your motherboard manual. Raising the voltage will effectively speed up the memory, but will also increase the heat.
   • Make sure the Case Latency in your BIOS corresponds with the CAS rating which your RAM supports - please see the Wikipedia article linked below for detailed technical information on working with RAM:
     http://en.wikipedia.org/wiki/Dynamic_random_access_memory
      

Using an Intel video card with Portal

If you are experiencing this issue upon entering the first portal, please refer to the Intel Video Cards with Day of Defeat: Source, Portal, Team Fortress 2, and HL2: Episode 2 topic.
Other users have found this forum thread to be helpful when using Intel video cards.
This issue can be a result of using an Intel video card that does not fully support features required by the game.  In some cases, it may be necessary to upgrade the video card being used.