Internet works only after jumpstarting with XP

Pertinent Info: I recently installed W7 Pro x64 on a second hard drive. I still have my XP Pro x86 install on the old drive.

Whenever I boot into W7, my internet does not work. Any webpage I attempt to access says "Internal Server Error." I've tried a few workarounds I read about on here, such as manually inputting the network and IP info and disabling/reenabling my network chip. I've also tried installing W7 drivers for the chip even though W7 found it right away.

Interestingly enough, if I boot into XP and try to use the net, all is well. If I then restart and boot up W7, it works there too. However, once I shut the PC down for the night and try again the next day in W7, it is back to not working.

I have an Abit IP35-e motherboard with a built in Marvell Yukon Generic Network chipset.

It probably isn't important, but I will say that the ONLY website that I can get to (in W7 before I jumpstart it with XP) is my ISP's site. This tells me that I'm connected to their network, but I guess I'm not being authenticated or authorized to use the net? I live in an apartment building that is prewired with ethernet jacks, so I can plug directly into the wall. I'm guessing that XP is sending out correct information for their servers to acknowledge me, but W7 is not doing this accordingly.

I know you guys get asked these things all the time and I would greatly appreciate any info you may have. Thank you.

Check that your dns settings are correct. From the command prompt, type

ipconfig /all

When I had it working in XP, I took down all the pertinent information from my network properties and plugged that into W7. No luck.

You could try disabling the dns client service itself and rebooting. Since you could access your isp homepage and none else, my guess is that there's a dns issue.

You could also try clearing the cache if you do not disable the service.

ipconfig /flushdns

One further thing to check is if your mac address is the same under both OS. If you connect directly to your isp without a router, an different mac (like 00:00:00:00:00 that is possible to have) could throw things off.

Thank you for the suggestions. Unfortunately, I'm in the same boat. I double checked the DNS I had and whether I leave it on auto or manually input, they are the same. I even changed my network controller physical address to no avail.

Is there anything else I can try?

Thinking about what is different with XP and 7, the IPv6 comes to mind. Try disabling by unchecking it in the local area connection status and the IPHelper service too. Make sure there is no Bonjour service present and running. Remove Windows Bonjour (mdnsresponder.EXE) with Bonjour Au revoir

Scan the system with MBAM.

Are you using the same ethernet port for XP as Win7? Your ISP may be interpreting a second MAC address as a second, unauthorized, PC.

Cox Sux, I mean, Cox Cable plays that game.

Yes, everything is the same for XP and W7. All I change is the HDD boot order.

The problem has been fixed. It has been blamed entirely on IE8. I've been an IE advocate for years, but this is the last straw that is pushing me to FF. I spent hours playing with settings only to find that changing the browser solves the issue.

I assumed it was NOT the browser because my connection in the tray always had a triangle on it. Why would the browser change/fix my connection problem?

My ISP requires you to log in the first time, and IE would never let me get to that page so I just assumed it was the connection. But sure enough, as soon as I opened FF it worked. Magic.

In IE, go to tools | internet options | connections | lan settings

Remove all checked boxes here, if there are any. See if that fixes your IE issue now.