So Wednesday, Windows (Vista) on my laptop did an Xbox (crapped itself and died). Woke it up from standby, started up, black screen. Forced the power off and started it up, black screen for ages, Windows finally starts, Event Log/Sidebar/Wireless all kaput.
Some Googling later, and found this. Long and short, run NETSH WINSOCK RESET CATALOG and restart. Job done, it all works again.