Sorry, I'm out of town or would have been quicker on the draw. SMTP server setting issues wouldn't cause the Internet issues (only sending email). Could have been an IP address issue (conflict with another machine, etc) or a DNS server issue, preventing you from resolving addresses properly. Both are issues that could have been resolved by restarting or time.
Honestly there are a ton of things that could cause something like this, which is why it's so hard to fix sometimes.