One of the best things about Firefox 3 was the arrival of the ‘awesome bar’, an enhanced toolbar that predicted where you wanted to go online based on your browsing history and bookmarks.

However, when Firefox asked users why they weren’t upgrading from Firefox 2 to Firefox 3 they found that the ‘awesome bar’ was a significant reason. Why on earth would something so useful put so many people off? The answer, you’ll be shocked to learn, is probably porn.

‘A lot of people contacted us to say that they had certain bookmarks they didn’t really want to have displayed,’ Alex Faalborg writes on Mozilla’s Blog of Metrics. 'In some cases users had intentionally hidden these bookmarks in deep hierarchies of folders, somewhat similar to how one might hide a physical object.’