I’ve been having issues with Verizon DSL randomly shutting down and not coming back up for an unacceptable length of time. Strangely it only happens on the Vista machine in the house. None of the Macs have this issue.
I think I discovered the issue. I had changed my settings in Opera using about:config. I had the “Max Connections Server” and “Max Connections Total” set very high and what I think was happening was that I was hitting the DNS server too many times and perhaps it was considered a ping flood or something similar.
I guess you can overdo browser optimization.