after i installed parallels 4, the airport utility could not detect my airport extreme (802.11n) wireless router. i could detect my older extreme running dual band at b/g and my airport express. obviously, the network was up. it was not until i uninstalled parallels (while the game i wanted to use mostly ran, there was one critical problem and it was slow), that i regained access to the router. i suspect, but don't know, that the removal of the two connection entries installed by parallels into the network pane caused the problem.
Parallels adapters which were removed, are not related to any physical connection, they are virtual interfaces, I suppose you can check for firmware updates, usually resetting PRAM may help, but please consult to Apple Store first
