All links on BBC website are underlined. Firefox only error.

The most likely cause is an extension, see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

It could also be a bad item in cache; clear it following the steps at How to clear the Firefox cache

I've got the same on safari... looks horrible!

in fact when I use firefox it's fine... only got the lines with safari!!!

cleared cache & all fine........!

Shift refresh solved the issue; it must have been a shortcut I had pressed by accident!