I just re-installed BF2 on my system which is running on Vista. I can connect to a game but once I am in I have about 5 seconds before punk buster boots me saying "Inadequate O/S Privileges". If anyone knows how to fix this problem please let me know. Thanks!
Try turning User Account Control off if it's not already off.
Go to Control Panel/User Accounts and then click Turn user account control on or off. I'm assuming that you are logged in as an administrator account if not then thats propably your problem
If you decide to have UAC on, right click on the shortcut, goto compatability, and check where it says 'Run this program as an administrator'.
Even though you may have an admin account, UAC prevents anything running with admin rights unless you specify this option. Turning off UAC as you have guessed, will run everything as admin as your account is so.
For any games running Punkbuster (multiplayer), it is generally advised to check the box I mentioned above, as this is what causes you to get kicked, or turn off UAC entirely. It's an issue with Punkbuster trying to scan RAM for cheating, but UAC not letting it. I think.