Does
M-x (c-state-cache-init)
fix it?
No, it does not.
I just got the problem again, while editing gtkutil.c in Emacs. There
M-: (c-state-cache-init) did indeed fix the problem.
So it sometimes help. I guess this only adds to the confusion...
You sent this message on March 22. That was the date Alan checked this
into the branch:
2010-03-22 Alan Mackenzie<acm@muc.de>
* progmodes/cc-engine.el (c-remove-stale-state-cache):
Fix off-by-one error. Fixes bug #5747.
The patch was merged to the trunk a couple days later. I don't know
whether you were running with it when you made the above observation