Original problem: Google Chrome wouldn't display ANYTHING. Not even its own settings page, hosted locally.
After much digging, I have a workaround: add a virus scan exception for Chrome. This works like a champ, but I don't like it as a permanent thing. Is there a better way?
===troubleshooting summary====
How I isolated the difficulty: I ran Chrome under Windows Safe Mode with Networking & it worked. Still wouldn't work inside a user account.
What I did prior to that & after that to troubleshoot: uninstall & reinstall Chrome several ways. Upgrade BitDef from 2012 to 2013, as well as various uninstalls & reinstalls.
Based on information I found here http://forum.bitdefender.com/index.php?showtopic=36113, today I did a clean install of BitDef 2013... but that didn't change anything.
Stats:
Windows 7 64bit, patched
BitDefender 2013, reinstalled today (Sept 1 2012) after uninstall [uninstall process below*]
Google Chrome, 21.0.1180.89, reinstalled Monday after uninstall [uninstall & reinstall process below^]
* BitDef process
+ uninstalled using Add/Remove Programs / reboot
+ ran uninstall program provided here on forum boards / reboot
+ ran CCleaner, updated today
+ downloaded BitDef installer from BitDef
+ installed BitDef
^ Chrome process
+ downloaded multiuser binaries from Google
+ uninstalled using Add/Remove / reboot
+ ran registry cleaner ****** from Google
+ installed multiuser version
========
As a warning: I've uninstalled & reinstalled these programs so many times already that, unless there's some new and different command or hand-wave along with it, I'm not going to do it again. There's a reason I don't work as a sysadmin any more.