Technical Difficulties

I installed Leopard onto my laptop this afternoon and now my email won't work. Luckily, Gmail saves everything, so I didn't actually lose anything, but now I can't even send an email unless I go to the Google homepage. And all of my emails have been wiped from my mail program. And Mail won't quit either. I tried to restart and Mail being open totally overrode my shut down command. Does anyone know how to fix this? I admit. I have a love/hate relationship with Apple. The guys at the Genius Bar are always just a little too condescending. It makes me want to shout something about not living in my parents' basement and getting some sun once in a while (I don't even know where the compulsion comes from, but it happens every time). I really don't want to go to them. Please help!