Another intermittent failure to connect to the network

Intermittent failure to recognize local network and internet in Vista.

Overview. System = dsl 2-wire connection, into Speedstream 5100 DSL
modem, into Linksys Etherfast cable/dsl router, connected to iMac, and
to Vista Home Premium Dell XPS 410 (E6300/ i945 chipset w/ integrated
NIC). This home network has existed fairly robustly for about 2 years.
Abruptly on 9/18/09, began experiencing a pretty random loss of ability
of the Vista box to find the local network or the internet connection.
The problem persists to this day. Throughout, the connection to the
iMac has stayed up. I have tried virtually everything (detailed below).
Due to the random nature of the outages, it is pretty tough to figure
out if any specific procedure has an effect. As of today, the only
candidate for a fix is to power cycle the ROUTER. This is in spite of
the fact that the problem persists when I bypass the router completely
and just connect to the DSL modem directly. My theory du jour is that
the network interface reset does not completely reset the network
interface, and that the only way to completely reset the network
interface is to drag down the NIC connection (with a powered-down modem
connection). While I wouldn?t bet the farm on this, it has worked 3
times in a row, which is a whole lot better than the 73 other things
I?ve tried.

Details. Problem began on 9/18/09. Periodically, and pretty randomly,
would lose the ability of the the Vista box to see the local network and
the internet. That is, the network icon in the desktop tray would show
no blue ball, and any attempt to connect would be met with an error
message. Tried ?diagnose and repair?, including resetting the NIC. No
joy. Tried power-off rebooting of EVERYTHING (modem, router, both
computers). This seemed to work some times. In retrospect, I think it
was the problem just randomly coming and going. Tried ?System restore?
to earliest available restore point (suspecting a toxic Windows update).
No joy. Tried a new system hard drive (reformat and clean install
from scratch). No joy. Went back to the old hard drive and reformatted
and clean installed on it. Loaded Vista from the Dell install disc (Feb
2007) and turned off updates. This is interesting. First time through,
got a network connection. So I did the whole procedure over again
(format, clean install, shut off updates). This time, no network
connection. Note that with these clean installs, there was no anti-virus
software reinstalled.

I noted that when you restart, and even when you turn the power ?off?,
power remains applied to the motherboard. So, SRAM register stacks are
not flushed by the act of turning the power off (unless the rest
procedure correctly flushes them). Anyway, I started turning off and
then unplugging the Vista box. Occasional success but nothing
consistent, and, again, in retrospect, probably just the random nature
of the problem.

Finally, I tried unplugging only the router and then repowering it.
This resets the router (which I don?t think is the problem because I saw
the problem when I connected the PC directly to the DSL modem with no
router. However, this also presents a load which drags down the NIC
outputs. This probably tells the NIC to reboot. Apparently this
hardware-driven reboot is more complete than the software-driven reset
in the network manager.

I have seen other posts remark that going to an external NIC card does
not solve the problem. I have a USB NIC dongle which I intend to try
after I get more of a handle on whether this modem reboot repeatably
fixes the problem. If the other posters are correct, then I suspect
that there is Ethernet hardware in the chipset which is inboard of the
PCI bus connection, and that this is where the problem resides, thus,
not affected by using an external PCI NIC.

This is a very nasty problem, hard to troubleshoot, and totally
cripples you. What good is a PC which you can?t connect to the

Comments from other poster????