Two network cards, one used. Card used on boot doesn't work

I have a PC with two network cards, but I only use one. The unused card is not plugged to the network.

After boot, regardless of which of these two cards is connected, it won't work. However, if I unplug the cable and plug it into the other card, it will work. Plugging the same card again won't work. It must be always the other card, regardless of which one was initially connected.

This behavior doesn't occur in recovery mode. It didn't happen on Karmic either; it only appeared after upgrading to Lucid.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: linux-image-2.6.32-21-generic 2.6.32-21.32
Regression: Yes
Reproducible: Yes
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-21-generic i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
AplayDevices:
 **** List of PLAYBACK Hardware Devices ****
 card 0: SI7012 [SiS SI7012], device 0: Intel ICH [SiS SI7012]
   Subdevices: 0/1
   Subdevice #0: subdevice #0
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: pablobm 1166 F.... pulseaudio
 /dev/snd/pcmC0D0p: pablobm 1166 F...m pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'SI7012'/'SiS SI7012 with AD1980 at irq 18'
   Mixer name : 'Analog Devices AD1980'
   Components : 'AC97a:41445370'
   Controls : 46
   Simple ctrls : 32
Date: Fri Dec 31 15:56:02 2010
HibernationDevice: RESUME=UUID=bce7e8e1-0f5c-4599-a790-a09d4e6de108
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
IwConfig:
 lo no wireless extensions.

 eth0 no wireless extensions.

 eth1 no wireless extensions.
Lsusb:
 Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 002 Device 002: ID 046d:c068 Logitech, Inc.
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: System Manufacturer System Name
ProcCmdLine: BOOT_IMAGE=/vmlinuz-2.6.32-21-generic root=UUID=d377dad7-3e29-4833-81d6-5bd2103e6cbf ro quiet splash
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
RelatedPackageVersions: linux-firmware 1.34.1
RfKill:

SourcePackage: linux
dmi.bios.date: 08/30/2005
dmi.bios.vendor: Award Software, Inc.
dmi.bios.version: ASUS P4S800 ACPI BIOS Revision 1011 Beta 001
dmi.board.name: P4S800
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: REV 1.xx
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 7
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAwardSoftware,Inc.:bvrASUSP4S800ACPIBIOSRevision1011Beta001:bd08/30/2005:svnSystemManufacturer:pnSystemName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP4S800:rvrREV1.xx:cvnChassisManufacture:ct7:cvrChassisVersion:
dmi.product.name: System Name
dmi.product.version: System Version
dmi.sys.vendor: System Manufacturer