Google Chrome sans fonts are all jacked up

Fenster

Operating system: Ubuntu Mint Ed^C^C^C Mint Linux 11.
uname -a: Linux tehlaptop 2.6.38-11-generic #50-Ubuntu SMP Mon Sep 12 21:18:14 UTC 2011 i686 i686 i386 GNU/Linux
Browser version: 16.0.899.0 dev
Window manager: Openbox 3.4.11.2

Okay, this is a real head-scratcher on my part. When I started Google Chrome this morning, all sans fonts within the browser were displayed bolded. This is true for both GUI elements and actual rendered pages. I've worked through a methodical series of steps to try and remedy this problem:

1. Check default font settings in Google Chrome and confirmed that my sans font wasn't bolded.
2. Manually changed all of my font families in Google Chrome to use the Droid* fonts (see screenshot, below).
3. Disabled, and then removed all extensions.
4. Deleted my .config/google-chrome folder.
5. Launched the browser in Incognito mode.
6. Confirmed my system-wide font selections and GTK theme using gtk-chtheme.
7. Utterly purge Google Chrome from my system and make a fresh installation.
8. Booted into Windows to confirm that this is only a Linux problem (it is).
9. Accessed other GTK applications - no problems there.
10. Search Google for any mention of this being a new bug or recurring problem. It is neither that I can see.
11. Checked my zoom in case I had accidentally zoomed in (I haven't)

Below are a couple of screenshots - click to view a larger size:

Fenster

No other solution presented itself in twenty four hours of trying, so I resorted to the nuclear option: rsync /home into my backup and reinstall Mint Linux. Took fifteen minutes to get my laptop back up and running. I'm still completely at a loss to explain what may have caused this.