This is a result of an internationalization extension in X11R4 and the
fact that HP is now using this extension. Emacs assumes that the
XLookupString function returns the same result regardless of the
<Meta> key state which is no longer necessarily true. Until Emacs
is fixed, the temporary kludge is to run this command after each time
the X server is started but preferably before any xterm clients are:
xmodmap -e 'remove mod1 = Mode_switch'
This will disable the use of the extra keysyms systemwide, which may be undesirable if you actually intend to use them.