I am stumped with a problem one of my clients has with their windows XP workstations. This is a small office environment, with about 6 XP Pro machines and a Windows 2008 Small Business Server. What seems to happen is, when they come into the office in the morning, their workstations somehow partially loose their network connection. They are still on the LAN, they can ping the server and other client machines, they can browse the internet, but their mapped drives and printers are no longer working. If they simply reboot their machines, everything works fine. One thing I tested, other than simply seeing if they could ping the server, was I tried to browse the server shares by typing in \\servername in the run command. Instead of a widow popping up showing the network shares, they get a connection window asking them to enter their network credentials. Again, if they reboot, and type \\servername in the run command, they see all the shares listed and are not asked to input their credentials. They have one XP machine that is hosting the main office printer. The same problem happens when I try to see the printer host machine from the other XP clients. When I type \\hostmachine-name in the run command...it asks for their credentials. Once they reboot, and I type \\hostmachine-name in the run command, a window pops up with the printer share displayed.
One additional thing is, they recently had to replace their DSL router with another DSL router (the first one stopped working and seemed to be dead they claim). The ISP sent them a new DSL modem/router, and everything seems to work fine with it. However, they claim that these connection problems started happening shortly after the new modem was installed. I can't verify that, and they can't really pinpoint the exact date, but that is what they claim.
The problem simply seems like their windows/domain credentials are somehow expireing during the night. I can't figure it out. I did visit the office two days ago late in the day, to try and diagnose the problem. At that time, I rebooted the machines (around 5pm) and the next morning everything was still working good...but after last night, they came into the office this morning and had the same problem again. I think I can rule out any sort of evening backup routine, as this appears to be more of a credential time-out or something like that.