We were using I.E. initially. I tried it in FireFox and it works perfectly. Every other page in IE seems to be OK, just the Zimbra webmail for her account that's messed up. She's content with using FF.
My account on her IE - looks fine
Her account on her IE - messed up
Her account on her FF - looks fine
Her account on another machine - looks fine
It's weird. But yes John, I cleared the cache.

That's an easy step to forget though!