I had the same issue. Actually it first started from sudden disappearance of network interfaces, i.e. ipconfig showed no interfaces. Nothing was installed or reinstalled at that point. I just had VPN (Cisco) connection, disconnected, then I was unable to connect to outside network. I found 3 network cards: Realtek, Parallels and Cicsco adapter, - all working fine. I tried to uninstall Parallels tools. It's been freezing in the begining of uninstallation. Tried to uninstall Cisco - same thing. Tried to update drivers for Realtek - the same. I manually removed Cisco VPN in safe mode. Did not help much. Then I removed Parallels Tools from the registry hive. Wohoo! Network came back. But I still install Parallels tools back. I also tried to experiment with Kaspersky. It does not seem to change anything.
Well.. my coworker just got into the same situation... Hm... Is it a recent windows update or something? Parallels is up to date. I still can't remove or update Realtek driver. System freezes. If I start installer and then try to reboot Windows, it complains about MCI Task hanging in the background. Looks like one of installer's jobs freezes.