Well if you are going to leave Go Daddy, at least get an explanation for what is happening so that if there is a next time, you will know what to do immediately. Everything is a learning experience, and if we didn't have these issues, we would never get better. Now that last error message looked like it was from your computer or service provider, that's not a server error. Of course all we can do is guess, but did you get a new router, or do you need to update the one you have ? Or modem ?
From what I gather this problem is caused by FF 3.0.1.... Do you believe that Check this thread on the FF site.
Interesting. I do have Avast installed as well, and I do get so outages , but they return quickly. Still you have shown differing error codes that point to different culprits. My opinion is still that with the traffic you have, it is still time to go to a "Grown Up" hosting company that can give you the personal support and growth that you need. It's just my opinion, but Go Daddy for domains seems to be great, but for hosting it's for noobs. (ouch)
Well, yesterday I got a nice email from Godaddy stating that I was using too much resources. At least they were honest about this. They also moved my site, once again, to a better server and gave me about a month to fix the problem. If nothing is done, they obviously advise me to purchase virtual dedicated or dedicated hosting.