First off make sure your Windows installation and all your drivers are up to date, especially the graphics driver. Some links:
ATI/AMD drivers:
http://sites.amd.com/us/game/downloads/Pages/downloads.aspx
Nvidia drivers:
http://www.nvidia.com/Download/index.aspx?lang=en-us
Intel drivers:
http://downloadcenter.intel.com/
Realtek drivers:
http://www.realtek.com.tw/downloads/
Via drivers:
http://www.viaarena.com/drivers.aspx
you can also get beta drivers here:
http://downloads.guru3d.com/
latest DirectX:
http://www.filehippo.com/download_directx/

Solutions for crashes and game freezes
- Create a shortcut for BFBC2Game.exe(it's in your game install directory), then right click on the shortcut -> properties -> compatibility and "Run this program as an administrator"
- Add +fullproc to the game's shortcut, example: "C:\Program Files\EA Games\Battlefield Bad Company 2\BFBC2Game.exe" +fullproc
- Open your antivirus software and exclude the BFBC2 folder that is in your documents from being scanned by the real time shields. Example on avast! version 6: Open avast! and go to real time shields -> file system shield -> expert settings -> exclusions and click add. Point it to your BFBC2 folder(the one that is in the my documents folder).
- Open up your settings.ini file in the BFBC2 folder in My Documents and check if the RefreshRate value is really set to 60(or whatever number your default monitor refresh rate is), if it's not at the correct value set it to 60(or whatever your refresh rate is, 60 is default on most lcd's). Should look like this: RefreshRate=60

ATI frames boost:
Open up Catalyst Control Center and under Gaming -> 3d app. settings -> Catalyst A.I.
- Set Texture Filtering Quality to HIGH QUALITY
- Disable Surface Format Optimizations

Nvidia frames boost:
- Go to control panel and uninstall "ONLY" the NVIDIA Stereoscopic 3D driver- should give you a boost in other games aswell

Decent FPS boost:
- Documents>BFBC2 and open up "settings.ini"
-*Change "renderaheadlimit" to 0 instead of 2
- This changes the amount of frames pre-rendered by your CPU for your GPU
*Note: If you have an ATI card set this to 1 to get the best performance, tested on Darth's machine...

Bigger FPS boost:
- Documents>BFBC2 and open up "settings.ini"
- Change "HSAO=true" to false (also settable in the in-game "advanced" graphics settings)

Other settings.ini changes that you can try:
- Overgrowth="medium" - This is for trees and the such.
- Undergrowth=”medium” – This is for grass and bushes.
- Water=”medium” - Map has alot of water? Drop the quality for fps gains.
- MSAA=”2" - This is Anti-aliasing. Lower value = higher FPS but lower quality. (jaggies)
- Shadows=”medium”- You can also set this to low to improve performance
- Textures=”medium”- Setting this to low can improve FPS at the cost of visual eye candy.
- Aniso=2 - Set this to 0 to disable Anisotropic filtering.

To run DX9 for improved performance (this also stops random crashes for some people):
- Documents>BFBC2 and open up "settings.ini"
- Add "DxVersion=9" to the list (without quotation)
- Alternatively, if you want to use DX10 or 11 change the value to 10 or 11.

To run the game in a window:
- Simply hit alt+enter and change your resolution to something smaller than your desktop.

For sticky/laggy mouse issues:
- Disable mouse acceleration in the game's mouse settings, and turn off Vsync in the graphics settings.

You can't look up-down and/or left-right:
- You've accidentally bound something to the axes that BF2 uses for looking around.
- Reset your controls to fix this.
- In future, when binding things to your mouse, pay close attention; if you move the mouse at all while binding, it will register & bind that horizontal or vertical movement axes, replacing your look ones.

Realtek onboard soundcards causing crashes:
Try doing this - Under the Microphone settings there is a setting for Noise Suppression and Acoustic Echo Cancellation, turn both of those off.

Possible fixes for problems with PunkBuster:
- check that your firewall is not blocking PnkBstrA.exe or PnkBstrB.exe processes access to the internet
- download and run pbsvc.exe to uninstall\repair Punkubuster Services: http://www.evenbalance.com/index.php?page=pbsvcfaq.php
- download and run PBSetup to update PB, instructions and download here: http://www.evenbalance.com/index.php?page=pbsetup.php

SOURCES: mostly on http://forum.ea.com/eaforum/forums/show/3827.page

=EM= Clan certified Bad Company 2 Configurator
BC2 settings described above(plus more, like changing the FOV, turret/sensitivity fixes etc.) can be easily set with this excellent util. Changelog and download links here:
http://forums.electronicarts.co.uk/battlefield-bad-company-2-pc/1009847-em-clan-certified-bc2-configurator-best.html

FOV Calculator:
This web app will calculate the FOV settings required for your specific resolution:
http://www.rjdown.co.uk/projects/bfbc2/fovcalculator.php

what about Nvidia crash?

Še editam, pride še par stvari noter. Ampak dej si prvi del še enkrat preberi, sem mal spremenil...