IIRC, we were experiencing "Corrupt packet flow" recently. Looks like it was a known issue w/ PB. Here's the latest releases from them, from this link:

News and Release Notes for PunkBuster for
Battlefield 2


Tuesday 11.27.2007 [4:15PM]

Version 1.479 of the PB Server for BF2 has been released to our PB Master Servers for auto-update and to our website download page. This is a maintenance release.

Monday 11.26.2007 [5:30PM]

Version 1.471 of the PB Server for BF2 has been released to our PB Master Servers for auto-update and to our website download page. This version addresses incorrect restriction kicking for "Corrupt Packet Flow" during map changes.

Saturday 11.17.2007 [7:15PM]

Version 1.466 of the PB Server for BF2 has been released to our PB Master Servers for auto-update and to our website download page. This is a maintenance release.