If your browser (I have seen it in Windows Chrome) incorrectly renders a specific font in italics you might be facing a corrupted font.
The first thing to do in order to resolve this issue is to determine the font being used. This is something you can find easily from chrome inspector (right click on an incorrectly rendered in italics word) which will reveal the current applied style including the font.
Once you know the font type then go to http://www.cssfontstack.com/ and select that font. Most likely it will be looking also in italics. See below how the whole page renders in italics:
This means that the particular font is corrupted as a result of a corrupted program installation or uninstallation.
To correct the issue just delete the font from C:\Windows\Fonts and bring it back again from a working machine (the file is a ttf which contains bold, italics, narrow and other combinations for example arial.ttf).