LAN keeps disconnecting and connecting constantly

For the past month I've been having this issue involving my computer disconnecting from and connecting to the internet.
I have Windows 7 (x64) and there is only one (that is: mine) PC connected to the router/modem (non-wireless). There is a periodic burst of "Identifying" with the spinning blue wheel then disappear again to try again a few seconds later. It happens once in every 10-15 seconds, constantly.
Btw, I do not have wireless connection in my house. I've already determined it's my computer and not a problem with the router/modem because it happens with both network connection (public and home). The cable isn't loose. Every time another computer is connected to the same connection as mine, that computer has no problems.
I have two network cards (Realtek and Marvell Yukon), but I disabled Realtek (red X is displayed on the icon) in order not to interfere with the other one.
Troubleshooting did not help.
Marvell Yukon driver is from 2012, but there ain't no new updates after that date.
I've tried to reset WINSOCK entries, IPv4 TCP/IP and IPv6 TCP/IP stack to installation defaults by typing following commands at the command prompt:
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netsh winsock reset catalog

netsh int ipv4 reset reset.log

netsh int ipv6 reset reset.log

But to no avail. I am not sure if my network supports capability of obtaining an IP address automatically. In any case, after reseting to installation defaults I noticed that TCP/IPv4 fields had became blank (IP address, subnet mask and default gateway) so I filled the blank fields manually, according to IP settings given from my network administrator.

The problem persists.
For the most part I've been living with it, but it's really annoying and if I can find a way to fix it that would be great.
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OS Version: Microsoft Windows 7 Ultimate, Service Pack 1, 64 bit
Processor: Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, Intel64 Family 6 Model 15 Stepping 11
Processor Count: 4
RAM: 4095 Mb
Graphics Card: ATI Radeon HD 3800 Series, 512 Mb
Hard Drives: C: Total - 152617 MB, Free - 43145 MB; D: Total - 238464 MB, Free - 105880 MB; E: Total - 238464 MB, Free - 84493 MB;
Motherboard: ASUSTeK Computer INC., P5K Premium

hello steampunk
i have the same issue as you do.
i tried the following, and it seems more stable now

do these commands from admin command prompt:


go to start ,search and type: cmd, right click on returned cmd.exe and select "run as administrator" at the prompt type:-


net localgroup Administrators /add networkservice
press enter then type:
net localgroup Administrators /add localservice
press enter then type:
exit
press enter and restart your computer

make sure you put a space after Administrators

although it seems more stable, I still can't get Diagnostic Policy Service running to repair my LAN connection.

good luck, this worked for many people

also this link

Windows 7: Diagnostics Policy Service not running - Microsoft Community

another possible problem with this disconnect reconnect issue.
my Intel driver for my PC LAN has a setting for "energy efficient LAN"
I turned that off.
testing now, so far it seems better

Thank you for your advice.
I tried both solutions, but, unfortunately to no avail. I don't have a slightest clue as to what causes this problem and now I am running out of solutions

If someone has any idea, I'd highly appreciate. Please..

I don't know what else to suggest.
I solve the same problem I was having by going to my LAN port in device manager.
From there opened properties, and I found a setting called "econo power mode", or something like that.
Un-checked it, restart.
The connection is solid and fast now.

So you have just one computer connected, but you have a network administrator?!?
Is this a home network and you are just calling the ISP guy or...?

because it happens with both network connection (public and home)

What two networks? How do you have a public and home networks, yet just your computer connected to the router, which is not wireless? Or do you mean that this happens if you connect your computer to a public connection somewhere, like at a cafe?

Callender, thanx for the advice, but I think the wires are not the cause of this issue, since when I connect my laptop to the same router/modem, that connection works smoothly.
Doctore, if you check the image above (my post #4), you'll notice that this motherboard features Two Gigabit Ethernet LAN controllers - Marvell Yukon and Realtek. My modem is connected to the former and I disabled the latter (because I heard that they may interfere with each other).

Is this a home network and you are just calling the ISP guy or...?

Yes, I was calling ISP guy. Btw, my PC is at my home and this is a home network (I just accidentally made another connection once, but it is disabled now - see the attachment). I do not have any connections to any public network like cafe etc...
In the first attachment one can see the issue described in my initial post. It happens constantly, every 10-15 seconds, all the time.

A few questions:

• Does this happen when you use the Realtek adapter, instead of the Marvell?
• Would you run ipconfig /all in Command Prompt and post your results?
• Can you open your router's set-up page and post a screen of the DHCP settings?

Thanks