A public service blog post, this time. I recently found that
had stopped working on my computer. When you typed an install command, all you saw was the spinning cursor, though it had definitely worked the month before.
I managed to track the reason down by a bit of googling and experimenting, but I thought I'd mention it here for posterity. I had recently installed the JSLint package for Sublime, and for reasons best known to itself, it had added its folder to $TEMP. (I suspect it was aiming at $PATH.) My TEMP "folder" was now two folder paths separated with a colon, which completely freaked out npm. I removed the extra folder path and npm went back to normal (after restarting the command shell, of course).