Event ID 1054...."Limited or No Connectivity" when logging into domain

What can they do and can they not do?

Can they all get to the Internet?

Can they all ping other machines on the LAN?

Are they all connected to the same switch?

Are other machines connected to the same switch working normally?

When they log into there computers in the morning they get the message "Limited or No connectivity" and you see the two network computers on the bottom right hand corner of the screen trying to connect.

NOTE: This happens every 2-3 days and not every day.

I have to either reboot the switch or remove the CAT5 cable and plug it back in to connect there computer to the network.

Yes, they are all connected to the same switch.
Yes, other machines are connected to the same switch and are working.

This is the setup on the network.....

Internet - Netgear ProSafe (Setup as DHCP) - Untangle Server - Windows 2003 Servers & Exchange

So you have a single LAN switch and rebooting it fixes the issues?

If all of your problem PCs are connected to the same switch and disconnecting/reconnecting them or rebooting the switch fixes the issue then I think you found your culprit.  Unfortunately switches are really 'repairable', rather you just replace them.  What kind of switch is it?

Yes, but it then comes back and I don't think it is the switch. I also have some 5-port Linksys switches around the office and just installed a new 5-port about a week or two ago when the issue started happening so I am wondering now if the new 5-port Linksys switch is causing the issue. The model # of the new switch is a EG005W so I am going to switch that out to see if it happens again.

I also just installed the following update on my Windows XP computer....MicrosoftFixit50492. I rebooted my computer and it logged in without a problem and faster then it normally does.

It's a Linksys Business Class.

It really sounds like a bad switch to me.  I have replaced more than a few 'business class' Linksys and D-Link switches in my day because they started acting flaky and unreliable.  Are they managed or unmanaged?

I also just installed the following update on my Windows XP computer....MicrosoftFixit50492. I rebooted my computer and it logged in without a problem and faster then it normally does.

Do all of your PCs have their updates managed by the network (via WSUS or a third party app)?  Have you tried this fix on another PC?

It's an unmanaged switch. I removed the 5-port switch I recently installed and replaced it with another one. I will see if that resolves the problem and if so I will buy a new switch.

No, I just applied it to mine. I am going to install it on two others and see if that fixes it to narrow down the issue.

The cause of the computers not receiving DHCP IP was a defective Netgear VPN Firewall so I replaced that and it resolved the issue.