Alt-x not working

[Steve Graham]

Yesterday it worked just fine, as in Alt-x run-scheme.

Today Alt-x doesn't do a thing, not even a comment in the window at the bottom.

Other Alt- combinations show a reaction from the system.

Have combed this newsgroup and Google without finding a solution.

Have tried deleting .emacs, then adding "(global-set-key (kbd "M-x") 
'execute-extended-comment)" to .emacs but still no change.

Same problem on original version 24.4.1 and new 24.5.1.

Would appreciate any hints.

Thanks, Steve