The new PD4 update that loaded yesterday (3810 Jan 23, 2009) seems to have brought back a bug that causes Parallels to have problems re-establishing an IP address after switching from wireless to wired connections. I had to reboot my entire MBP (including the Mac OS) this morning in order to get it to re-establish. Usually, I open the MBP from sleep and everything automatically reconnects...
Brian
Brian