Wide space in Firefox

[piratas]

The white space in my firefox suddenly get much wider than before. See attached screenshot. I was install and uninstall firefox extensions, and this happened. Now I disabled all extensions, and my firefox still display white space strangely.
Any ideas? thanks

[piecewise]

I'm having the exact same problem, the space character seems to be rendering about five times as wide as necessary! It absolutely ruins the layout of any page and is driving me up the wall.

I've tried other programs and it seems to be confined to firefox, but it's not just pages in firefox (ie it's the address bar and tooltips and menus and everything)

Has anyone had any luck with this? I've tried searching but "firefox wide space" comes up with a bajillion irrelevant responses...