I use Chrome as my brower, and before that, I used Internet Explorer.  They both worked fine with AC.  I always write my stories in Word and then copy/paste them over when posting to AC.  I don't use the text editor because it messes up the formatting from Word, so in my preferences on AC, I have "Use tinyMCE WYSWYG editor" unchecked.  Do you use the tinyMCE editor thing?  That could be why you're having issues with copy/pasting and then trying to edit.  I just have to add in the tags by hand to do any formatting, like putting something in bold or italics or centering it.  It's kind of a pain in the ass, but at least it posts right that way.