I opened IE this morning (this machine is IE7 on Windows XP) and nearly all the text on every page was in italic. Now assuming that various companies including Microsoft, Google, and my employer hadn’t suddenly decided that italics was the new marquee I decided the fault was probably localised to my computer.
The solution turned out to be in the fonts. In the past couple of days I’ve been messing around with the Microsoft Office installation on this computer and I think at some point some of the fonts have got unregistered. Internet Explorer was picking the “nearest” font to it’s preferred one and coming up with the italicised version of the sans-serif font I’d expect.
To fix this, open the Fonts folder in Control Panel and choose “Install New Font” on the File menu. Select the folder C:\Windows\Fonts and then press the “Select All” button and then the “OK” button. A lot of prompts will probably appear that a particular font is already installed, just click OK on these, but some fonts which are in the folder but not installed will be installed. Once this is complete open Internet Explorer and check it has worked.