I used to have a ton of problems with my network adapter. It would always encounter and error saying "default gateway unavailable"
I recently reinstalled windows and updated the nvidia drivers for my motherboard and when I looked into the drivers folder in C:/windows/system32/drivers, I saw that there was a driver that says nvm62x64.sys and nvm64x64.sys. When I uninstall the drivers and leave the stock windows ones, i only get nvm62x64.
I think this is significant because the fix I found to this problem on a windows support forum was that if you download the vista driver for the motherboard and extracted it to folder, you would find a file named nvmfdx64.sys and you would then rename that to nvm62x64.sys (the win 7 file name). Then you would replace the windows driver with the aformentioned vista driver and everything worked for me and never had that default issue again.
so I am wondering what the heck is that nvm64x64.sys file that nvidia put in there and I think this may be the cause of the problems because everything works without the particular file.
I was having a ton of disconnections with my network adapter as soon as I installed Windows 7. Not a single thing had changed aside from doing a clean install to Win7Pro from WinXP MCE. My connection was always solid as a rock under WinXP.
The problem was very frustrating, my network connection would lose connection randomly and I would have to disable then re-enable the connection to get it working again. I noticed the "default gateway unavailable" message as well whenever this occured.
I have an ASUS M2N32-SLI Deluxe motherboard with a 590SLI chipset from Nvidia.
It took a while to find a solution to the problem as Win7 is still fairly fresh but I found one eventually.
In the device properties for my network adapter there is an option called Receive Side Scaling under the Advanced tab. I set that option to Disabled and instantly all my network connection dropping ceased. It has been solid since.
I am using the nForce 15.51 drivers for Win7 64bit.
I have a Belkin Wireless Network Adapter and had a similar issue. It turned out that the adapter wasn't officially supported by Windows 7. It's not a big deal because I dual boot between Win 7 and Vista. Both are 64 bit OS. I just used the Vista x64 drivers. Vista and Win 7 both use the same drive model. Wasn't a problem after that.