Menu bars all gone!

[Kevin O'Brien]

I am having a very annoying problem. None of my applications display
window bars any longer on my Kubuntu 64-bit Natty installation. The
problem first showed up on a couple of applications about a month ago,
and I hoped the upgrade to Natty would fix it. Instead the upgrade
seems to have spread the problem to all application windows. Any idea
how to fix this?

Thank you,