Problems seen after leaving a Windows 7 computer on overnight:
- The Ethernet connection was in the "disabled" state and claimed the cable had been disconnected (it hadn't).
- ipconfig /all hung permanently and did not respond to Ctrl-C.
- The network control panel took five minutes to open.
- Anything that needed administrator access would not work. Task Manager would not show processes from all users, the Services control panel would not open, and I could not enable or disable the network interfaces. Windows would usually show a window asking for confirmation to perform an administrative task; it did not appear.
- After a reboot, the user could not log on. The computer had to be powered off and restarted. This may be PEBKAC, but has enough changed in the boot process that rebooting no longer necessarily means rebooting and a cached bad OS state could have been reloaded?
My initial thought was that a conflict between the wired and wireless network adapters might have occurred when the DHCP lease ran out, since the computer uses Ethernet but has wireless capability, so I disabled the wireless interface. The User Account Control failure suggests the problems are deeper.
From the Event Log: Around midnight, there are two DNS lookup failures for msftncsi and Symantec Live Update. After that, a large number of services fail to respond to svchost, starting with upnphost. It's possible that the failure to ping msftncsi led Windows to believe the network was down, but that does not explain why plug-and-play and a number of other services failed or why Windows thought the cable was physically disconnected. There was no sign of any earlier problem that would have led to the DNS failure.
The computer is less than a week old, so cruft should not be an issue.
What might have broken? I am not familiar with Windows 7's internals.
Start an Internet radio stream on iTunes. Go away and have lunch or do some chores. You can listen while you work. Come back in thirty minutes and move the mouse. Frequently, the stream will stop and you will get the DNS server timeout error.
I have not tried that.