Actually, I open Network every time I go on line (eg, it's open right now); I can connect from that panel and monitor time online as well as whether stuff is loading. And Modem is indeed my top item.
Clearing those caches still seems to have done the trick.
In fact, earlier today I showed a colleague with a new MacBook Pro running Lion how to do that, and it likewise cleared up a whole bunch of problems he was experiencing in Word and Mail.
