I recently went from Opera 7.11 to 7.23. Now when I load a particular website I get a very strange behavior. The pages are valid HTML 4.01 strict, btw.
The layout is the kind of 2 column floated div arrangement that generates a peek-a-boo bug on IE unless the line-height is explicitly declared.
What happens in Opera 7.23 is that the floated div contains tabular data and the table width gets mis-calculated so that the div hogs the entire width of the containing div as well, overlapping the contents of the two.
Well, at least that happens sometimes. When it does, a refresh or two usually gets a proper rendering from the browser.
I've never before seen a rendering bug that isn't consistent like this, one that "usually" goes away on a refresh and indeed does not always show up on the first page load.