I take it that you are running the latest patch (1.22) for BF2? I'm almost certain that this patch addresses issues with the 7800 series cards. Also as far as trying driver version 81.90, I have read of people having the same issues as yourself and they had tried that version. Many say that the 84.43
drivers and above have solved their problems. Guru of 3D
will provide you with even later beta versions, feel free to try them. Failing that, I would suggest that you use Driver cleaner, and be sure to follow kemps guide to the letter, if you fudge the cleaning process you may be in for a world of grief.
As a last resort, if the latest drivers/BF2 patch or driver cab cleanout don't fix your issues, I'm afraid you may need to RMA. Keep us posted, and best of luck