OK sorry it took so long but everytime i try and start a campaign, i says that the game has encountered a problem and must close. It gives me the option to send an error report, dont send an error report, and to debug.
I also tried to download the patch, but it says "failure to open new file C:\Program files\Lead Pursuit\Battlefield operations\campaign\balkans\rta40420.
As for my computer, it has MS XP professional, with intel pentium 4, Cpu 2.80 ghz, and 504mb of ram.