I recently noticed that the main menu of a site I work on had an approximately 5x5 px white box at the beginning of the main menu that shouldn't be there. Some pages had it while others didn't. I tried to right-click and "Inspect element", but my context menu was the kind you get when you right-click on a Flash object. Huh? I didn't have any Flash on that page.
Since the box was so small I zoomed in on it and at my browser's maximum magnification, I could discern "Skype AS" and some other text like "Detect". At first I thought it was Skype's (in)convenient browser add-on that senses phone numbers on web pages and makes them "callable" using Skype, but then I realised the two pages that showed the weird behaviour each had a badge of Skype code to show whether or not a given Skype user is on or offline at the moment. Sure enough, when I removed the code, the white box went away.
The thing is, this code has been unchanged for almost a year and only now am I noticing the white box. Has Skype changed the code called by the badge? I expect it has, but I haven't investigated. Suffice it to say, it's pretty irritating when code from a third-party "all of a sudden" interferes with your site's layout. It was like a zit had just appeared on my site. Naturally, the display isn't consistent across browsers. Firefox doesn't show it while Chrome and IE8 do.
It turns out you are using an outdated browser and my site might look a bit weird for you. (images are off colour, text gets cut off, layout is wacky) This is because your browser does not implement web standards. Please consider an upgrade.