Windows – Block extensions from being installed in Google Chrome

Bon Gart's answer explains the native way to do it, which only involves signing into your Google account. However, if you don't want to sign up with Google, or store your data with them, you can easily go ahead and archive your profile folder.

It's stored in the following location:

• Windows XP: %USERPROFILE%\Local Settings\Application Data\Google\Chrome\User Data\
• Vista, Windows 7: %LOCALAPPDATA%\Google\Chrome\User Data\
• Mac OS X: ~/Library/Application Support/Google/Chrome/
• Linux: ~/.config/google-chrome/

All you have to do is:

• Quit Chrome
• Copy the User Data folder contents somewhere safe
• After re-installing your OS, install Chrome*
• Run it once and close it again
• Copy the backup of your old User Data folder over the existing one in your new OS installation
• Start Chrome again and you should be running like before.

_{* I'd advise to install exactly the same version of Chrome though. If you install an older version, your profile will not be readable. Also, when switching OS, this method might not work.}

Have you tried syncing your chrome to an account, and doing a wipe/fresh install? Perhaps the sync data is bad and it might be good to get a fresh sync going on a new account.

As you stated, the culprit was likely the experimental settings in about:flags which makes sense. Hard to always see the far-reaching impact changes there might have. Odd that it affected all extensions though.