I just bought BC2 during that steam sale and had a few issues too. One fix is to go to the .ini file (documents>bfbc2>settings) and force the dx level you want. It will say dxversion=auto by default. Change the "auto" to "9" then click save and make the file read only (right click on settings.ini>properties>check read only and click ok). There are also more graphics options in the ini file. You can change all the settings this way.
YOU the man advanced setting work great downloaded msi afterburner on the highest settings not lag or fps drops YOU the man