All kinds of "The registry is in use by another process, timeout expired"
This kind of situation didn't happen before the discription of Steam.exe became "Steam Client Bootstrapper (buildbot_winslave04_steam_steam_rel_client_win32@winslave04)" and the SteamService.exe , seems 2/3 updates for Windows actually is for Linux(Ubuntu?)
It mainly takes place on Valve's games and Source SDK E.G. sometimes you run a Valve's game such as CS:S, a window will appear and tell you some content(s?) that includes "The registry is in use by another process, timeout expired". Source SDK has this problem too, and it may cause you can't build a map but run the game