"Check for Updates" hangs for a long time then fails. There is no record in the HTTP proxy server's log indicating that Parallels ever attempted to connect to their servers so I assume Parallels just dropped packets on the wire and hoped for the best. Mac OSX, like Microsoft Windows, has a global http proxy setting all apps should use. Outside of home environments you generally can't assume direct access works. Both 2.5 and 3.0 have this bug.