Given that Firefox 14 is the current beta version, there could be a bug that you're seeing. Have you tried disabling all of your addons or temporarily using a new profile?

I had the problem with FF 14 develop when I went from XP to Windows 7 Pro. I tried every fix in the forum plus uninstalled it using Revo Uninstaller and did a clean install, nothing worked. Then I said to myself "duh" and right clicked on the FF desktop icon and ran a compatibility check. Windows said FF 14 was not compatible with Windows 7 and is now running FF14 in the XP mode (a feature of Windows 7 Pro). It works fine now.

What is odd is that I have 2 other computers running Windows 7 Pro but FF 14 runs fine in Windows 7 on them.

Since going to V 14, found that after a couple of minutes use, keying in to fileds (e.g. Google search input) becomes painfully slow. I have to hold the key down for 2 - 3 secs before it 'takes', for EACH CHARACTER!

Noted the 'running FF14 in the XP mode' & tried this & it apperas to have worked.

THX

Which security software (firewall, anti-virus) do you have?

Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that works.

I was able to install FF15 but I had to remove all my anti-virus, anti-spyware, etc. using http://www.appremover.com/

Next time I'll try it in the Safe Mode and see how that works.