Windows 7 has just recently started losing all network drives, although Internet connection is not affected. I have a small home office with 2 other PCs (one running Vista, one XP) plus a network printer. All was working and networking perfectly. Now, all of a sudden, the Windows 7 machine cannot see the rest of the network. If I unplug and then replug it to my network switch it rediscovers the network and printer and works fine until next boot, when the same thing happens. The rest of the network (connected through the same, unmanaged gibabit switch), is unaffected.
I'm running Windows 7 Pro x64 on the affected machine. The built-in NIC is a Realtek PCIe GBE and the drivers are the latest from Realtek (7.6.820.2009)