Reopened, Closed as dupe (as proposed)
This meta question on strange keyboard behavior was closed for clarification (and currently has a delete vote). It has since been updated to clarify that the problem was due to the (little known?) SE keyboard shortcuts - which can cause very puzzling problems if one is not aware of them.
As such, I propose to reopen then close it as a dupe of a prior related question on unexpected behavior caused by keyboard shortcuts. This will help improve matches to searches on such puzzling problems when they arise for other users. That no one on our meta recognized these shortcuts as the source of the problem seems to imply that giving this wider exposure here would be a good idea - not only to avoid wasting time debugging such strangeness, but also to give the shortcuts wider exposure toto those who may find itthem useful.