One thing that has been driving me crazy about this Mac (besides RDS not working) is the silly behavior of tabs in Firefox. Imagine a logon form. You click on the username field and enter your name. You hit tab and then enter the password. You hit tab again and... eh? Where did my cursor go? To the address bar.
I don't know why Firefox does this, but I found a site with the answer:
Proper tabindex in OSX Firefox
And if you are like me, you may not know where your Firefox preferences are stored. You can find it under the Library/Application Support/Firefox/profiles folder. Not the Library folder at /, but the Library folder under your own account.