OS X :: Trying A Firewall Has Knocked Me Offline?

A couple of days ago, I thought I'd try a 3rd party firewall to beef up security on my 2008 MBP running 10.6.2 on an ethernet connection using a router (nothing changed there).

I installed Little Snitch, tweaking its settings (don't remember what I tweaked) to customize it to my preferences as I went thru two 3-hour demo periods. Then I uninstalled it (using its own uninstall). I also tried Noob Proof to see if a free program might serve, but wasn't happy with that one, and uninstalled it using AppCleaner.

At some unknown point during this 24 hour period, I lost my internet connection, and I can't get it back.

Things I've tried:

-Ran network diagnostics several times - it says I've got a good connection, and Activity Monitor shows small amounts of data being sent and received.

-Turned Mac's firewall off & back on a few different times. Can't get online even when the firewall is off.

-Turned on the guest account and logging into it. Can't get online thru the guest account either.

-Re-installed Snow Leopard just in case it might re-set whatever is wrong.

-Looked at LOTS of logs (including Little Snitch's log) to see if I could find the source of the trouble, but while no dummy, I'm also not an expert at reading logs.

-I've also tried connecting to Software Update for a direct connection, thinking maybe it was a browser issue, but can't get connected to anything, anywhere, anyhow.

Any ideas?