Boot in safe mode
Remove NIC from device manager
Remove the NIC and any other cards you have
Reinstall NIC only! (use motherboard graphic card if you can, otherwise put it back in)
Second thing to try
goto Start > RUN > CMD > and type msconfig
Uncheck everything in startup and reboot and see if it works.
If it does work then the problem was a application running that was conflicting.
Have you had any bad storms or power outages lately? NIC's are easy targets for power surges..
I've already resinstalled Windows - as i mentioned - no network adapters are listed in the device manager.
Its onboard and also not showing in the bios (was there before)
I've cleared CMOS using the jumper and pulling out the battery - nothing worked.
I think its dead (maybe i should try a BIOS update as last thing)
Now i'm using an wireless usb adapter to connect to my router.