When Firefox updated from V10 to V11, I ended up with both installs. I deleted both versions with Revo, and cleaned the registry with CCleaner. I then re installed V11. It loads to the 1st splash page, but will will not do anything else. (ie go to another page and can't connect to the internet). As soon as it loads I get this error message. '''Could not initialize the application's security component. The most likely cause is problems with files in your application's profile directory. Please check that this directory has no read/write restrictions and your hard disk is not full or close to full. It is recommended that you exit the application and fix the problem. If you continue to use this session, you might see incorrect application behaviour when accessing security features.''' I don't see a "Profile directory" anywhere in Firefox directory. 1/2 hr before this started, with 10 and 11 installed, everything was fine. Chrome and IE8 both work fine.