BleepingComputer.com: Dropping Connection

I am dropping my internet connection several time per day, since I’ve had the computer
(January 2010)
To fix the problem, I go through the following steps:

Open network sharing, Local area connection, IPv4 & IPv6 show no internet access
Rest of the house (4 computers) are still connected and doing fine, 2 are wireless,
2 are hardwired, mine is hardwired, NOT wireless
Select properties, client for Microsoft networks,
Configure, advanced tab, link speed and duplex,
Change value back and forth to either 100 Mbps Full Duplex or auto negotiation,
Select OK, see the Network symbol in the network and sharing center
Change to “identifying”, then connection is restored.

I will have to do this about ½ dozen times per day, sometimes
5 minutes apart, sometimes hours, always after I have logged off.

At one point in the past, I accidentally selected 1.0 Gbps Full Duplex and the
Computer froze and I had to use safe mode and system restore to roll back one day
to clear that problem.

What is causing my connection to constantly drop?
What details do I need to supply to help troubleshoot?

Some of the larger details:
Powerspec Model B817
Intel core i5 CPU 750 @ 2.67 GHz, 2.79 GHz
4 GB Ram, 64bit OS, Windows 7 Professional
Network Adapter: Intel 82578DC Gigabit Network Connection Version: 11.0.41.0
(update attempt says it’s drivers are current)

If I let the computer attempt to fix the problem itself when the connection is lost,
It generates a report with the following information:

Details about network adapter diagnosis:
Network adapter Local Area Connection driver information:
Description . . . . . . . . . . : Intel® 82578DC Gigabit Network Connection
Manufacturer . . . . . . . . . : Intel
Provider . . . . . . . . . . . : Intel
Version . . . . . . . . . . . : 11.0.41.0
Inf File Name . . . . . . . . . : C:\Windows\INF\oem2.inf
Inf File Date . . . . . . . . . : Monday, June 22, 2009 3:05:28 PM
Section Name . . . . . . . . . : E10F0.6.1.1
Hardware ID . . . . . . . . . . : pci\ven_8086&dev_10f0
Instance Status Flags . . . . . : 0x180200a
Device Manager Status Code . . : 0
IfType . . . . . . . . . . . . : 6
Physical Media Type . . . . . . : 14

Issues found
The default gateway is not available Fixed
The default gateway is a device that connects a local network or computer to
the Internet. A broadband modem or router is usually the default gateway.
Reset the "Local Area Connection" adapter Completed
This can sometimes resolve an intermittent problem.

just a comment
most routers only allow u 4 connections, do you lose connection when everyones on line, u can check this by looking at your routers makers specs

the drops have happened when I've been alone and when others have been on, no patterns.

another comment
u must have ipv4 to get the internet dont worry about 6 unless ur on a domain check the settings for this

"I will have to do this about ½ dozen times per day, sometimes 5 minutes apart, sometimes hours, always after I have logged off." Logged off what?

Does it happen while you are actively doing something? Like watching a video on YouTube or or downloading a file?

Do you have DSL or Cable?

And umm a router with a 192.168.x.x IP with a subnet mask of 255.255.255.0 can handle 253 network connections. =)