Why can't I type lower case 'a' in Safari when entering text in a field? If I open Safari and go to www.google.com and type in a search the letter 'a' can't be typed.  I have to press shift+a in order to type a capital letter a but can't type a lower case 'a'.  I'm typing this message in Firefox so clearly the key on my keyboard is functioning correctly.  

I can type lower case a in the url bar area but not in other text boxes.  I can't type it on apple.stackexchange.com or on duckduckgo.com.  No text areas on any website seem to let me type lower case a.  However, it works fine when I use Firefox.  

Any thoughts?  I'm using OS X 10.10.4 and Safari 8.0.7.
I had exactly the same problem, and after disabling extensions and restarting Safari it went away.  I then looked more closely and found that I had set the letter lowercase-a as the keyboard shortcut to allow flash in ClickToFlash.  Apparently this made it not work as a character in any text boxes in Safari!  I now have all the extensions back on but without that key shortcut, and everything is working fine!

BTW, this is clearly a bug in ClickToFlash, since the default key to make flash full-screen is lowercase-f, but I can type that fine in any text box.