BF2 lag/beeping

Ok, iam having problems in my game battlefield2 where as its been lagging on multiplayer and single player. It lags in a way that if i move a tank left it continues to move left without my control, likewise just running ect... And sometime my computer beeps while its lagging. I have ran the game without a internet connection on single player so its not internet. Ive ran my radeon 1600 512mg on the lowest settings and that didnt help. Its not over heating because iam running at 59C. I have 2 sticks of ram = too 1 gig which may be the problem because i just recently had this problem with the game and iam thinking one of the sticks may be bad. So i was wondering how i could test to find out which isnt working, or if u have any other ideas on what causes game lag on single player please tell me

Motherboard:MSI MS-6702
CPU:AMD Athlon 64 3200+ ( not overclocked )
Memory: DDR PC3200 / 1gig of ram

 

only post once dude, the mods will be on ur butt tomorrow lol