From a newsgroup post: "A correction is needed to a setting in PROSet when running the driver for a Microsoft OS from the February 2001 software release version 5.0 (individual e100b driver version 5.40.11). In the settings in PROSet, please turn APT off to eliminate any hardware error messages being added to the event log.
To turn off APT, please go into PROSet and click on the Advanced tab. Choose Adaptive technology from the middle left column and change the value on the right side to OFF. Exit PROSet and depending upon the OS, reboot. This workaround is for 82557 based adapters only."
We found this to happen if we disabled the (second) onboard NIC, but it was still first in the binding order. After the change of binding order (and for good measure also unbinding TCP/IP from the adapter) the errors stopped. [Network and Dial-Up Connections -> Advanced -> Advanced Settings]