I got a call on Saturday because two Vista laptops couldn't get onto the file server, nor could they get on the network. An hour later, through no intervention on my part, both computers were working fine. On Saturday, there is very little network traffic, and most of the 30 workstations and laptops on the network were off.
Monday morning, the same 2 laptops could not connect to the server nor to the Internet. Investigating, I discovered that one of the computers failed its automatic Windows Update over the weekend. I re-ran the Microsoft Update on one laptop (from files previously downloaded). After the process finished, I rebooted the computer. Nope, still not connected. An hour later while troubleshooting this problem, both computers suddenly were able to access the file server, get email, and access the Internet. Everything was fine until this morning (Friday).
This morning, same problem, same two Windows Vista Ultimate computers could not access the network. I couldn't ping the server, couldn't ping the router. One of the two computers had been off overnight, and one was on. Both worked yesterday when the users went home. After about 2 and a half hours of troubleshooting one of the computers and restoring it back to an earlier restore point, and waiting another 40 minutes after the restore, both computers were again working. It was like magic. There are no tell-tale signs in the event log. There are a few occurrences of the Event Id: 4226, but they do not correspond (timewise) to when the problem appears...and I would think that a reboot would resolve that issue. Rebooting the failing workstations and/or the server does not resolve the issue.
Obviously, I would suspect the server since its the common denominator between the two computers, especially since both computers fail about the same time, and both computers start working again, about the same time. But aside from the typical Windows Updates, nothing has recently changed on the server. And its difficult to believe that any changes that would affect connectivity would only affect these two computers.
This environment has 30 workstations/laptops connected to a Windows Small Business Server 2003 server which provides the network functionality for DHCP, RRAS, Exchange, DNS, and ActiveDirectory. The workstations/laptops are comprised of a few Windows 2000 Pro computers, several Windows XP SP2 & SP3 computers, 3 Windows Vista Ultimate computers and 1 Windows Vista Business Premium computer. The problem occurs with 2 of the Windows Vista Ultimate computers (Dell). Its always the same 2, and nobody else on the network experiences any loss of network connectivity. Two of the Windows Vista Ultimate computers were purchased together and have (supposedly) identical hardware. Only one of those is failing. The other one that's failing was purchased 6 months later. One computer has Service Pack 1 installed, the other one does not.
Anybody have any ideas? Your help will be greatly appreciated.