Don't know what's going on, but began experiencing this -- as best I recall - about 60 days ago, in a time when devs were working on refactoring some of the rendering... and maybe tweaking .css

Doesn't happen often, but still see it occasionally...

Occurs in all these under W2k: FF 1.5.0.2, Moz 1.7.8 *and* IE 6.0.28nnnn; don't remember seeing it on Konqueror on Linux