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.
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. some other error fixes good luck