Something is seriously wrong with patch 220.127.116.1179. None of the maps are being shown in the Maps selection box on the Single Player -> Custom -> Create screen (even though the files exist in StarCraft/Maps/) and therefore the game cannot be played in Single Player mode. (Everything was working right before the patch happened.) (Interestingly, at least the Challenger map is available in Multiplayer mode)
Update: After uninstalling and reinstalling StarCraft (why is it 6.5GB?) the issue remains.
Update: After removing Documents/StarCraft, Uninstalling StarCraft AND battle.net, and then reinstalling StarCraft (6.5GB downloaded AGAIN) the issue remains.
Update: I can play the game by loading a saved game only. Unfortunately I had not saved a game at the very beginning, so I can play only the end of a game… that is too bad.
Update: re: system specs: I’m away from my PC right now but it’s Windows 10 on i7-4770K.