If you're confident you completed a good BIOS update, check your BIOS settings.
Also, did you uninstall and reinstall the Intel LAN driver?
It may be a good idea to uninstall all the Intel drivers and reinstall from fresh downloads.
I'm not having any issues on my DX58SO with the latest BIOS installed. You should go through a troubleshooting procedure to determine if the board is the problem or something attached to the board is causing the issue. Disconnect everything from the board and check to see if you still have the issue. It could be a bad board. If the board checks out with everything removed, then reinstall everything one at a time to see if you can find the cause.
I'm running Windows 7 64bit Professional.
I format the SSD drive prior recovery BIOS update then Im using latest LAN driver.but I haven't uninstall and reinstall LAN after latest recovery BIOS update.
I also try with microsoft wireless keyboard & mouse but same problem.
MB: Intel DX58SO LGA 1366
GPU: Evga 460
CPU: Intel Core i7 950 (NO overclocking CPU)
HD: Intel SSD 120GB
PSU: Corsair 650W
MEM: 2Gx3 Corsair CMX6GX3M3A1333C9
Keyboard:DELL (wired usb)
Mouse:Microsoft (wired usb)