There apparently is a card floating around using the 82573 chipset. Somehow this card has its EEPROM programmed incorrectly and can conflict with the newer driver that is in FreeBSD 6.2. The driver version is 6.6.6 and in my opinion the version number fits absolutely correctly.
Here is a blurb from Jack Vogel, the FreeBSD EM driver maintainer:
“There is also a hardware eeprom issue on systems with an 82573
type NIC on SOME systems. There is a utility to fix that, if you
have a problem, and have that NIC email me and I can send that
out to you.”