Title explains much of everything - it's happened once, but it solved itself quickly last time after a few reboots. The message says:
Steam.exe (main exception): Unable to start Steam Engine:
*SteamStartEngine(0x34e824) failed with error 200: Fail to connect to
any GeneralDirectoryServer, WinSock Error 10061 "Connection Refused"
Rebooting doesn't help much, this time - has this happened to anyone else before?