Whats the Problem ?

[coltrane]

Mar 22 17:14:09 darth kernel: e100: eth0 NIC Link is Down
Mar 22 17:23:01 darth kernel: e100: eth0 NIC Link is Up 100 Mbps Full duplex
Mar 22 17:50:17 darth kernel: e100: eth0 NIC Link is Down
Mar 22 17:50:21 darth kernel: e100: eth0 NIC Link is Up 100 Mbps Full duplex
Mar 22 17:50:25 darth kernel: e100: eth0 NIC Link is Down
Mar 22 17:50:27 darth kernel: e100: eth0 NIC Link is Up 100 Mbps Full duplex
Mar 22 17:50:47 darth kernel: e100: eth0 NIC Link is Down
Mar 22 17:50:49 darth kernel: e100: eth0 NIC Link is Up 100 Mbps Full duplex
Mar 22 17:51:05 darth kernel: e100: eth0 NIC Link is Down
Mar 22 17:51:11 darth kernel: e100: eth0 NIC Link is Up 100 Mbps Full duplex
Mar 23 09:14:33 darth kernel: e100: eth0 NIC Link is Down
Mar 23 09:15:17 darth kernel: e100: eth0 NIC Link is Up 100 Mbps Full duplex

I have never seen this before

[Feztaa]

looks like your nic isn't working.

[coltrane]

its not a constant error though

[Killer_Penguin]

Either a bad nic, or the port that you are plugged into is going bad.

[imported_Psycho]

Could be a cable too...

[trickster]

Your nic has a bipolar disorder.

[Schotty]

try a different card and cable to the hub/switch/router

More than likely its the NIC, but the problems look as if the cable MAY be playing a role. But if I was the owner of the box, I'd run to CompUSA and grab a new NIC.

[elovkoff]

another guess - if this workstation is on LAN then probably you should set it to autinegotiate the speed with switch instead of having it on full duplex (especially if your switch has problems with full-duplex)

[PeP]

I had the same problem on debian squeeze with kernel 2.6.32-5-686 and two different interfaces:
Intel Corporation 82801DB PRO/100 VE (LOM) Ethernet Controller [8086:1039] (rev 81)
Intel Corporation 82557/8/9/0/1 Ethernet Pro 100 [8086:1229] (rev 0c)

I fixed it disabling auto negotiation and forcing ethernet parameters using ethtool:

/etc/network/interfaces

iface eth1 inet static
    # (other options here)
    pre-up ethtool -s eth1 speed 100 duplex full autoneg off

[camelrider]

Before buying new hardware it may help to be sure your cable is properly seated at each end. Next remove the ethernet card, check the contacts, then re-seat it in its slot. You might even try another slot if one is available. Then if there's no joy try a different cable. Then if still no joy a new card is probably in order.