During the first few hours I was playing CS1 I was having constant issues with my Xbox 360 controller where certain button presses either weren't registering or were doing something other than what they were mapped to.

It turns out that having the steam client open simultaneously was the culprit [like many PC gamers I keep steam open in the background even when I not using it, for example when playing a GOG title] - so as a helpful public service annoucement to anyone having Xbox 360 controller issues, try exiting steam before starting the game up - it solved all of the issues for me.