Whenever I try to click the "multiplayer" tab in SpringLobby (0.12) I get the error msg "couldn't get your spring versions from any unitsync library" and can't join games.
I get the same message when I try to watch a replay or load a savegame.
I'm running 0.80.2; I had this problem earlier with 0.79.something.
The point is to delete any files evil spring might have scattered throughout your system. Try opening infolog.txt in spring directory and look at the beginning - it has a list of some directories (Docs&Settings\currentuser etc). Manually go though those dirs and delete any suspicious file. Definitely anything which ends in .lua