Curious keyboard (?) bug

[John Chambers]

For compatibility with some machines of the folks I'm working for  at
the  moment,  I've  "upgraded" one of my home machines to RedHat 8.0.
Among the usual learning experiences that are inevitable, there's one
very  bizarre  misbehavior.   The right Ctrl key seems to get "stuck"
sometimes.  That is, the software behaves like the right Ctrl key  is
permanently down.  However, if I touch the left Ctrl key, the problem
goes away and the keyboard works again.

One reliable way to make this happen is to use the Ctrl key with  any
mouse button in an xterm, to get a menu. The menu works, and then all
the software on the system behaves like I'm  holding  down  the  Ctrl
key.   But this only happens with the right Ctrl key, and again it is
fixed by pressing the left Ctrl key.

Sometimes it happens when I know I haven't touched  either  Ctrl  key
for  some  time,  so  it's  probably not a hardware problem (though I
suppose it could be marginal hardware that worked before by  chance).
Also,  the  right  Ctrl  key  seems  to function normally inside most
windows; only xterm seems to produce the bug reliably.

Has anyone seen this?  Google found a few scattered references to the
problem, on RedHat systems ranging from 7.2 to 9.0, but I didn't find
any suggested fixes.  My previous software on the system (which was a
real  jumble  of  releases,  with assorted things upgraded whenever I
decided to do it) never had such a problem.

Maybe I'll just have to try to train my subconscious to treat the two
Ctrl keys differently. That will require overcoming years of training
of course.