try running your m/b disk if you have it to re-install the driver for the NIC. CCleaner is a gr8 free tool for quick registry fixes too.
I would run your anti-virus progs 1st off though. Access maybe denied due to a virus running in your memory.
Spybot 1.5.2 is out there for free & should find any trojans that damage drivers in system32
Resore just evades the underlying issues.