Spent many hours yesterday trying to figure out why my game doesn't work properly on some computers - keyboard events get stuck, "Key is down" condition always return true for some keys, "On key released" is never triggered etc.
Turned out that Evernote Web Clipper extension was causing all these bugs.
Oddly, this was only happening with C3 runtime, in C2 runtime keyboard was working fine.
This is a very popular extension with millions of downloads, so be aware.