This was quoted from the nVidia Forums, two users verified it worked. I don't know why it magically worked for them, maybe because STEAM is not running... not sure. Worth a try.
Finally figured out a solution to make BFBC2 work in a surround monitor setup. First thing you will need to do is make sure Steam is not running. Then, you will need to edit the BFBC2 "Settings" file. It is located in this folder:
Local Disk (C:\\Users\\[user name]\\My Documents\\BFBC2
Change the following settings to the values that are bolded.
Note that the resolution and refresh rate must match exactly with what the current settings you have in your nVidia control panel. These values will vary depending on how much bezel correction used (if any) or may only require the default surround resolution. For example, my spanned desktop resolution is 6000 because I used a value of 120 for each of my bezel settings for a total of 240 lines of bezel correction. I am using three 24" screens that each have a native resolution of 1920 x 1080. So, 1920 x 3 = 5760. 5760 + 240 (bezel correction) = 6000 total horizontal line count. Pretty simple, but I just wanted to explain it anyway The vertical line count remains 1080 for me. Your numbers will vary depending on the size of your monitors.
After you have changed all of the settings, make sure to save the changes and close out the file. Restart BFBC2 and it should now work. The center screen will now show the opening video and then you will see the main screen and now you will be able to select on everything. Go to the settings and OPTIONS and make sure to select the resolution and refresh rate. You do this to ensure that the settings are saved properly to the Settings file that you just edited. And that's it. You should now be able to play BFBC2 with your surround gaming set up.
And yes, I am using nVidia's latest 275.33 WHQL certified drivers and this solution works!
Let me know if you have questions and let me know if it works...